The word is that you will have to update to the latest official firmware, then the game will update you again to at least 5.55. 5.55 employs firmware verification to ensure your running legit copies of games. 5.55 is already on GI Joe but is not a web release yet.
Furthermore, there are apparently no plans for hacking 5.55 because the PSP Go will ship with 5.7, which is what they are planning as the next CFW release. Things could change based on demand though. Might not be M33 but GEN that releases 5.55
So no, when its released, there will probably be no way of playing it on modded firmware. This will change if/when perhaps a patch is made to the game itself, or a 5.55+ CFW is released. But if you want to play it on day 1, your likely gonna need OFW on your PSP. For some PSPs (pandora proof ones), this could mean losing your mod permanently.
-DeathCom