Nope, it has lots of hurdles beyond psionics. How to do defiler magic, what to do with clerics when there are no gods, absent core races are all major hurdles. And there is a rabid fan base who will become hysterical if WotC get anything "wrong".I think that they're sure about moving forward with it. It is the easiest old D&D setting that has new content and themes.
"Easy" is a clean new setting. Does MtG have a post-apocalypse world by any chance?
And the polls suggest that, whilst Dark Sun is quite popular, Planescape is far more so.
If they had better ideas they would have put them out first. WotC are not sitting on a bunch of alternative psionics. But even if they did then it's at least 3 months to put it through the UA process, and a 3 month delay, with no guarantee of success after that time, is very expensive for a project that is already underway.I think that they'll keep playtesting psioinics until they get it right, instead of abandoning it. If they actually want to make a Dark Sun book, they wouldn't wait to write the book until they had the mechanics 100% down. They didn't wait to write Eberron: Rising from the Last War until they had the Artificer 100% of the way completed.