I agree, particularly with regard to the NHL. The prospect of playing hockey on mushy ice in July and August is not appealing and, not to mention, probably presents some kind of an injury risk to players (I'm thinking a spate of blown ACL's as players attempt quick pivots on skates that get relatively stuck). The NBA might be able to finish its season if it cuts the playoff field down to eight or maybe even four teams (just play the conference finals and finals).
The idea I'm kicking around for MLB is spring training starting in mid-June, season opener mid-July, 84 game season (48 intradivision, 30 interdivision with no home-and-home and 6 interleague, regular season concludes mid-October, postseason concludes mid-November with Northern tier teams possibly having to relocate for the WS, ie. Twins home games in Miami). If "Spring" Training 2020 2.0 can't start by mid-June, stick a fork in the season.
NBA Commissioner Adam Silver is SI's Sportsman of the Year since his decision to cancel started the wave of cancellations.