Given how real estate projects are financed and the nature of the eventual proponent(s) involved in any broader redevelopment scheme here, the cost is nearly irrelevant in the question of teardown vs. retrofit.
I would imagine the more salient concern for the baseball team in that respect is the value of time -- after two years of an unprecedented amount of disruption to the players and staff (and the costs associated with playing at both Dunedin and Buffalo), I imagine the retrofit is the preferred option at this point. Shapiro himself has also been pretty clear that the players really disliked being moved around (understandably) and playing in subpar physical environments and that it was an issue they had to discuss with free agent targets.
For a team that has now entered its prime window of competitiveness, and given what the team has recently gone through, I don't imagine relocating is at all desirable to them at this moment.
