Speculative theories of some without any basis and misinterpreting P. Spencer's words about the convenience of XSeries PRO "RIGTH NOW".
1-The most solid information is the FTC vs MS/ABK docs. They foresee a new generation for 2028.
They also emphasize the need to be more flexible with the characteristics of the hardware than it already is and not focus only on a fixed one and to make it more similar to the Windows PC model.without losing the benefits of development for fixed hardware.
That tells me that they are open to launching more models with different specifications and that there is already a plan.
Honestly, and been saying this for months now if not longer...the best move for Microsoft going forward is to make Xbox-like gaming NUCs and laptops, but running full Windows. They already bring all of their games to PC Day 1 anyway; if PC Game Pass is really growing as much as they say, then they could leverage that with the next line of hardware. If they actually revamped Windows Store into something attractive for PC gamers, that'd drive more game purchases directly through their storefront. Not that MS probably care about giving a bit of money to Valve through Steam sales, but they should be more concerned about if/when Valve try re-attempting Steam Machines again based on the successful Steam Deck model, and get compatibility in Linux good enough to where most PC gamers feel they won't need Windows.
Plus that model gives them an excuse to increase the hardware prices to where they get some actual profit margins, where they can control production better by not needing to spend so much on manufacturing at volume trying to match Sony and Nintendo production rate, they can still bring their hardware R&D from console over, give the boxes a slick Xbox gaming UI and seamless switch to regular Windows desktop for those who want it, can get more experimental with hardware designs (particularly in the laptop area), potentially partner with OEMs to design variants (think like what Valve did with Steam Machines but successfully, or 3DO with Goldstar, Panasonic etc. but successfully, or the various Hitachi/JVC/Samsung etc. Saturn variants Sega had back in the day), and have incentive to release updated models every two years or so (making better use of the All-Access program).
Additionally they'd no longer have to deal with being endlessly compared to Sony and Nintendo, would have no reason to not bring virtually all their games to PS/Nintendo/PC since Xbox in this case would be more like a PC than ever (but every now and then, still have the odd PC exclusive like Flight Sim or Gears Tactics which by virtue would still give "Xbox" an exclusive or two here and there), and maximize revenue in their gaming line as a result. Simply way too many upsides with very few if any downsides.
Well, unless you're a diehard Xbox fan still obsessed with MS beating Sony in the space of traditional consoles and the business model thereof. But Microsoft seem like they want to shift away from that. My question is, how much does Phil Spencer actually want to shift from it? And if he doesn't, is it due to some misplaced sense of pride? Would higher-ups eventually force his hand, if that were the case? Interesting times ahead in those regards...
2-Phil did not categorically deny the possibility of an XSeries Pro, he only spoke in terms of the present. Imagine announcing the development of a new model 2 years before it is launched...

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If there is a plan for an XSeries Pro, it will certainly not be announced today and that will cause damage to sales of the current models. Whether or not there is a plan to launch an XSPro, we will know when Sony announces its PSPro, not before.
The only issue here is that an Xbox Series Pro doesn't really help Microsoft the way a PS5 Pro does Sony. The fundamental problems with Xbox, a Pro console doesn't magically just fix them. The 3P performance differences between PS5 and Series X are already minuscule; even supposing a scenario where the Xbox Series Pro is more capable than PS5 Pro both on paper and in practice, is the difference going to be in any way significant enough to suddenly boost market presence for Xbox?
I don't think it would. And, like I said, there are other aspects of Xbox that would have to be addressed simultaneously; if anything a Pro model could exacerbate some of those problems, not help them.
Honestly, they'd be dumb not to launch first. So much so that I'd be more surprised by them launching same holiday season as PS6 then I would be if they spun off Xbox hardware. I am not suggesting they will spin off hardware. Just recognizing two things: 1) existing digital libraries are a huge draw if faced with a choice between similar specs at the same time; and 2) 360's launch was a great time to own an Xbox (RRoD notwithstanding).
If they get a year or two head start, every traditional console early adopter will be at least tempted.
I mean, they
could. But they could also get Dreamcasted. At the end of they day, being the new, powerful kid on the block doesn't mean anything if you don't have enough of the big games the market wants, preferably exclusively, to drive traffic to your new machine before the competition is ready to launch.
For Microsoft to enjoy the benefit of what you're saying, they'd have to hope that 1: Sony's back years on PS5 are dry and boring in terms of meaningful exclusives, 2: more enthusiasts gamers (the hardcore and core who are usually early adopters) aren't on PC and have settled in by then which connects with, 3: finding a way to have some actual console exclusives again (i.e only on Xbox, not PC Day 1) if in fact enthusiasts presence on PC is even bigger by then than it is today.
Without the combination of those three things, a 10th-gen Xbox that's trying to exist on the traditional console business model, launching a year or two ahead of PS6, won't don Microsoft any long-term favors. BC doesn't mean anything much because Series S & X had that and it hasn't done too much to move the needle for those systems. I don't think either launching in 2019, with the library at launch they had in 2020 (virtually 99% multiplats), would have made much of a dent by the time PS5 was ready to launch in 2020, or when PS4 exclusives like TLOU2 and Ghosts of Tsushima would launch in the summer.
It'd of been a Dreamcast 2.0 situation all over again. Without addressing the three points mentioned above, IMO it'd still be a Dreamcast 2.0 situation for MS launching 10th-gen machines a year or two early, if they are going to position them as traditional consoles on that business model.