Suggestion A
As a player with 3 level 55 characters with 10k,20k,40k exp respectively, I hope they keep the high exp needed to level up after lvl 55.

For example: EXP needed
55 to 56= 83000+ EXP

56 to 57= 85000+ EXP*

57 to 58= 87000+ EXP*

*Examples of exp values.

This way, a new map for high levels plus a higher level cap could be a win.
Since it gives more incentive for people to really commit playing PL on a daily basis and purchase plat to get 2x/3x elixers.
This would also prevent current CS prices for lvl 55 equips from crashing.

The new map could have lvl 60-65 equips.

Currently, it is too easy to get to lvl 55 and most people just give up after that, since there's not really anything to do. Getting to lvl 56 seems pointless only to get a helm. Just my opinion.

Suggestion B
There could be in game adverstising from other companies. Create vanity items like Coca-Cola shield/Hats/Weapons, Macdonald's hat/burger shield etc.

This would give more players more things to play for.
I'm citing the recent Sony Ericsson Button event, large spike in the number of players.

Both suggestions will hopefully increase revenue for the awesome people who createdPocket Legends.