I think it would be cool if every second year we just got a big standalone game that didn't have a toybox section or a starterpack/base (3.5, 4.5, 5.5 etc). Like how they said the Speedway/Toybox Takeover expansions almost got released separately as their own game rather than being labeled as a 3.0 expansion pack.
This would give them that extra year to make sure the toybox mode is bigger and better (with playsets catered to Disney, Pixar, Marvel and Starwars fans equally) for 4.0, 5.0 etc.
The .5 series would just be one huge playset/expansion game (8-12 hours long rather than 2 hours) that isn't franchise restricted and doesn't include a toybox. Whilst they continue supporting the previous years .0 edition.
For example ...
-3.5 Speedway: with over 50 tracks.
-3.5 Splatoon: because we all know how super popular that toybox level was recently
-3.5 Diablo 2.....
Or maybe .5 could focus on just one franchise, "We took a vote and Hercules is really popular this year so here is 4.5 Hercules edition". "Included is a Hercules playset, a battle arena expansion pack, a powerdisc pack with a rideable Pegasus, and Phil team up disc ... oh and of course Hercules, Meg and Hades are now playable figures" -JV.
I know lots of people who get bored with the game once they finish the playsets, because they don't enjoy the toybox mode. The .5 series would help bring those people back to the game, I think!!
SO yeah, what do you think???