That's what I assume is going on here too. And you're right about PF being a pain to DM - it's basically like DMing 3.5 D&D - neither of which I will go back to again. I'll happily DM BECMI or 4e or 5e games, but I just can't sit down and DM a Pathfinder game. Even though I spent years running 3e D&D I just don't enjoy doing it anymore.
I think this might be true, but I think they need to be careful. What they're proposing for PF2 looks to be as big a shift in that game engine as the shift from AD&D 2e to 3e (or for those who think the shift from 3e to 4e was bigger, that one - I personally think 2e to 3e was the bigger shift but mileage varies on that question). They're the experts and they can do what they want but to me that seems a bit wrongheaded - it seems like it would have to alienate the existing player base that you need to evangelize for you. This has played out badly at least twice in the history of RPGs that I can think of - first when White Wolf shifted from their original WoD to their new WoD and changed everything at once - setting and rules. And then when D&D shifted from 3e to 4e and did the same. They lost the biggest advocates for their game by doing so - the players - and it took a long time for both games to win people back. (Of course both companies also had a patronizing "we know what you guys really want - you don't know what you want" tone to their marketing around their edition changes as well, which likely didn't help them either. And I say that as someone who likes 4e as a game engine - the community relations around it were not well handled.)
The only major switch I can think of on this order that has worked is the switch from 2e to 3e - and 2e was in a state as a product line where it had shed players, the company that had managed it had run it into the ground (and themselves along with it), and there was an audience hungry for D&D and were willing to try something substantially different as long as it wasn't "too" different. In that environment making a major change to game between editions makes sense because either it works and you get a successful game line out of it or it doesn't and you haven't really lost anything other than your development work.
Pathfinder seems to have a large enough player base that that kind of shift seems risky. It would definitely seem like a streamlining of the game might be in order - but more on the order of the shift from 1e to 2e than a wholesale set of changes. Maybe the 3.5 engine just can't be streamlined that way without changing it substantially to something else, but still it's a big risk.