I will give two examples.
Spirit watch.
New mechanic (or Bmap):capture the flag +domination
Use the orb to capture the three nodes within the time before the orb explodes.
-Once a node is caped it can not be decaped.
-If your team manage to capture the three nodes ,gets 100 points.
-Orb resets on x minutes.
-If the orb drops can be picked up on a time limit or resets.
-Kills counts for the score.
-Orb explosion (or reset ) knocksdown for 5sec(no damage).
Legacy of the foefire.
New mechanic (or bmap):deathmatch +lord
Classic deathmatch with the twist that once the lord is killed you can not respawn any more.
-Nodes are inactive.
-Kill count rather than points.
-10 min duration in case that no lord is killed.
Now, the question for the players is ,would you like to play something like this ?or would you prefer just new maps with new mechanics.
And for the devs in case some one is reading,how hard will it be to implement new mechanics on existing maps?,i guess that it will probably easier than start a map from scratch.
You could even get capricorn back with a new mechanic.(:P)
Anyway thx for reading.