If Bogaerts' future profile indeed trends to a move off shortstop -- to 2nd or 3rd or LF -- I don't see an opt out resulting in any GM giving him a giant Tatis or Lindor-type contract. Tatis, who at age 22 already moved for a spell to right field, isn't maybe a good Xander comp anyway... leading the league in home runs at age 22.
It could be X opts out just to get a decent raise and extension to stay where he really wants to, in Boston. The total dollars and years will certainly be affected by what happens in the upcoming agreements, between owners, unions, and ultimately, free agent shortstops.