I think the drone hardware cycle is beginning to flatten out, much like smartphones and computers before that.
The P3P/A was a HUGE step up from everything before, and IMHO turned the corner on offering a drone that anyone could use, that does all the fundamental tasks really well, and had only very minor compromises.
12 months later, the P4 is a worthy annual upgrade on DJI's part, and either one of the reduced-price P3 offering or the P4 are natural and easy upgrades for a P2V+ owner who skipped the P3 last year.
P4 isn't a must-have upgrade from P3, but anyone who does upgrade will find some nice perks.
IMHO, that's all you can really expect from a 12 month upgrade cycle on fairly mature hardware - it's not like it's been the last few years, where the upgrades were revolutionary. With Lightbridge, mile+ range, 20 mins flight time, VPS, POI/Waypoint/etc, the P3P/A are fantastic drones, and all the fundamental boxes are checked.
At least for now, the upgrades are going to be real, but incremental. I'm a P3P owner who honestly doesn't really take advantage of the full potential of even the P3P... I'd love a P4, but the upgrade just doesn't make sense for me, much like the Inspire - there's some great stuff on there that I'd love to have... but it's not worth paying for in the real world.