Let's step back and think logically about this. What you're describing is the best case scenario, right? Nothing changes and everything you were ok with/enjoyed is still there. There is a worst case scenario however that they could do things like 3DS did (since there's precedence) that certain games will only work on the new system. It is also possible that developers what to hit x graphics or whatever on the new console and due to time constraints poorly adapt it to the lower hardware which could lead to worse looking graphics or much worse framerates we currently experience since they now have to test two different setups and one would think they would prioritize the more powerful unit first. I'm not going to argue whether this will happen but you can't hand wave that it never could happen or that there's no downside to this when it's definitely possible.
Well, let's indeed step back and use both what was said (reportedly) during the presentation meeting and common sense.
Not sure why we would use 3DS though, not similar situations, markets or company.
First, in the meeting, it was apparently clearly said that PS4K optimized games would also run on PS4 (and before you or anyone jump on the "significant sacrifices", it has been amended, and I'm sure that a drop from 1080p60 to 1080p30 with perhaps a few less effects would indeed be described as significant by many). So no talk of exclusives (which clearly wouldn't make sense anyway).
Second, about common sense, which scenario makes the most to you?
- A dev having the "weaker" platform with a 55m+ install base as lead and targeting a satisfying common experience (1080p30 stable), knowing that the stronger one will improve from there and also be relatively easy to scale being an iteration, not a new platform
Or
- Targeting baseline (1080p30) on the strongest hardware, knowing you will be likely to either have a shit show on the weaker hardware, or drop specs so much that the F-up would be obvious to all?
When (actually IF) we ever see a 1080p30 "barely hanging there" PS4K game and its PS4 version at 900p30 struggling, then I'll call BS.
Until then, I call overreaction.