Current PS Vita PCH-1000:
Future PS Vita PCH-2000
Judging by the slight alterations, does it matter which version to buy? Nintendo 3DS, Nintendo 3DS XL, and Nintendo 2DS have several alterations that affect buying whichever one, but I don't see buttons being the ultimate factor (Although they say the PCH-2000 will have extended battery life).
One'a these days, it's gonna be mighty easy to upgrade an internal battery without havin' to buy a new system.
'Cept even the original PSP has a removable internal battery, and therefore the possibility to upgrade has long since been a thing.