the total number of pts (including every villa for every night of the year) for each resort is fixed and cannot change.
here's some history for you (for one of the most extreme changes). you can see some of the reallocations in the links below:
https://disneyvacationclub.disney.g...6/dvcresorts/2016-OKW-Pt-Cht-FINAL-121614.pdf
original pt charts from 1994 for OKW (thanks to webmasterdoc).
if you wanted a 1BR at OKW for 7 nights in may 1994, it would have cost 200 pts. if you wanted a 1BR at OKW for 7 nights in may 2016, it would cost 199 pts.
20+ years later and your pts still get you the same value. how's that for no inflation?
OTOH, if you wanted a studio for 5 nights sun-thurs in early december, your 35 pt stay cost in 1994 has now increased by 43% to 50 pts. weeknight stays have taken a hit...but if you just stayed 2 nights on a weekend in early december at OKW, your 34 pt stay in 1994 dropped a bit to 26 pts.
if you typically stay for 7 nights, i doubt you'll see any big changes (although early dec is popular enough that it won't surprise me if they move it to a different season.)
timesharing definitely involves a risk of change. that's true. but for the most part, if new buyers just buy a few extra (5-10%) - that should cover most of the small reallocations...