Remathilis
Legend
Not that there's any way for us to know for certain, but I would wager that a PF2 that was just an updated PF1 would sell a lot more than the PF2 that they ended up with. I mean, it's not like those players originally went to PF1 because they were sick of 3.5 or anything; they went to PF1 because they liked 3.5, but PF1 was better. Ergo, that audience would happily switch to a better version of the same thing.
If PF2 only targets the people who bailed on PF1, then that's a much harder audience to capture, because there were lots of different reasons for them to quit. For every GM who gave up on PF1 because of NPC complexity, there's a player who gave up on PF1 because of PC complexity, and two more who gave up on it because of balance issues. There is no possible product that will bring all of those players back, but there is a possible product that would get their existing audience to buy more books.
Its anecdotal, but of all the DMs I still keep in contact with.
Two (myself included) bailed on PF the minute 5e came out and haven't looked back. FWIW, I looked to see if there was anything from PF2 that I could use in my 5e game, but decided most of it was too incompatible and not worth conversion.
One played PF up to 2e, but is giving up on it for 5e.
Another is not converting to 2e and will continue to use 1e. For the record, he dislikes 5e as well.
So just from my informal sample of four, PF2 got 0 converts based on the playtest. The plural of ancedote is not data, but amongst the conversations I've had, no one was excited for the game. I hope Paizo can find new converts (possibly 5e players who want something crunchier) but no one in my circle is keen to support them. Best of luck to them.