I think what I would want as a 5e player, and what Pathfinder 1e fans would want are two different things.
For the actual players of Pathfinder I think the following would have been more to their liking...
A Cleaned up version of PF1e. What I mean is that all the current classes (or most of them, especially those out of the APG and probably the ACG, UC, UM, and Occult adventures) are found in a core rulebook. Most of the GOOD Feats are kept and many of the trap feats are tossed. The rules are slightly streamlined (so, perhaps the 3 action round type idea that PF2e floats), but for the most part it remains a LOT like PF1e.
They don't go the route they did with PF2e (or appear to be going at least) that they took. They make PF2e a PF1e cleaned up and streamlined a little, but for the most part almost exactly like PF1e with added classes, feats, and equipment.
Don't toss out the baby with the bathwater, build on the system you already have and make it better with what you've already created. Simplify a few things, but overall have the exact same system for PF2e as you do for PF1e. Make it more of a AD&D 1e to AD&D 2e type transition than a D&D 3e to D&D 4e type transition.
For a 5e player who isn't all that much into Pathfinder....
Simplify...simplify...simplify.
Reduce the number of feats. Reduce the number of skills. Make it easier to figure out Attack Bonus so that it basically goes with a +1 every 2 levels (so 1/2 level = BAB). You have a higher number than 5e as your base, but it's low enough to keep things more in perspective. Keep classes clean. If you do need to have more than the number of classes in the first core, keep it limited to the PHB and APG classes. Make the classes themselves more simple and easier to figure out bonuses and numbers.
OR...simply make adventures for 5e and drop the entire PF2e thing.