I'm pretty sure there's precedent for staggered releases of the core rulebooks. 3.5 and 3rd edition were like that, from what I remember, which actually allowed some third-party publishers to swoop in and fill the gap a bit for a few months.
Also I find it amusing that the things you list as "positive" changes to 4th edition are the exact things people like myself didn't like about it. Considering Pathfinder is far and away the best selling tabletop RPG today, it seems people who liked the 4e "improvements" are in the minority.
I'd also add that when I bought the 4th edition books, I was shocked to see they lacked rules for crafting (or anything not related to combat, really), stats for metallic dragons, or really any information about monsters other than their most basic combat statistics. So, again, precedent.
After seeing 5th edition played, and talking to the designers, I'm much more hopeful for it. At the very least, my group is going to try the starter once we're done our current Pathfinder campaign.