A climate-based calendar makes too much sense. Who really wants to watch a game in the heat and humidity of Florida in July, let alone play one. Or freeze your cajones off in Minnesota in February? If you take climate into account when scheduling, you can run whatever calendar season you want. I'm not sure why we haven't done that.
This also might make "travelling support" a thing in the U.S, if during the spring/autumn seasons the matches are geographically bunched to allow a quick milti-hour train ride or drive part of an MLS weekend getaway.