Seems to be a common theme these days. This is essentially the same situation as what happened with Peter Wichers, Chris Amott, Peter Lindgren, etc. Sure, Chris Amott came back, but that's the exception...
Picture yourself in Ola's shoes - would you want to do even more touring? Most of the time, Soilwork gets on really shitty bills in the US where they have a short set and they have to open up for most (if not all) of the other bands. Look at what Soilwork has already achieved on a musical level - what would your motivation be to continue if you had that kind of legacy behind you no matter what, and if you had to be stuck on tour constantly?
You've got to really enjoy touring to be in a band that is put under these kinds of expectations by the label and fanbase. If you don't, then it's probably better to make a shift towards doing more production/writing and less touring. That usually means quitting your band.
Soilwork is one of my favorite bands ever, but I don't envy their lifestyle, and I can relate with Ola's decision and I wish him and the band the best.