While in negotiations the only consideration is projected costs and revenue. Now the fans factor into that of course (they are the revenue) but, while ill will can take time to overcome, the assumption is the fans will be back so they’re hardly a significant consideration. (And I’d wager none at all in terms of “doing right by the fans” although I think a push towards revenue sharing and across the board competitiveness is a win for fans.)
I can’t think of anything that will get the majority of fans to give up their sport(s)/team(s). Being noncompetitive can hurt a lot at a team level but that’s about all I can come up with. Everything else I can think of: cheating, fixing, attitudes, ownership, lockouts, trades – sometimes it takes longer than others but they’re all forgiven. Though if the cost per game to attend or, more importantly, watch at home got high enough that would probably do it but it would have to be pretty dramatic.
What would fans do without their teams? Well the NBA is going to find out if they don’t get this resolved and either salvage this season or get the next on schedule.