If you are talking about a map with new rules to replace Summoner's Rift, then no.
The current "map" is League of Legends. Changing that would probably end in disaster. We have enough balancing problems as is.
######By "new rules" I mean: turrets in different places, different lanes, different mobs, etc
If you are talking about a re-skin, then yes!
Summoner's Rift has had a few re-skins over the years. Initially, the argument against that was "making a re-skin requires our artists to draw everything from scratch". Recently, they've started making more skins for Summoners Rift, so that argument is no longer an issue.
Instead of having those skins during special occasions, we could have them anytime we wanted.