They did this in an acceptable way in Brotherhood. Wouldn't have been right for you to start the game decked out in the Sword & Armor of Altair, maximum pouches, etc. And the attack on the villa made it a believable way for that to happen.
I think the best way for this to be accomplished in Revelations is just a simple, unstated walking away. Ezio's going on a long voyage, over mountains terrain and desert. He doesn't want to be burdened with all that equipment. So he leaves it behind at Tiber Island, taking only one of each items what he needs.
Now of course, logic says he'd take Altair's Sword, the Dagger of Brutus and the Seusenhofer Armor set with him, so they'll have to figure out how to reduce that back down to a base level. Probably the Templars will take that stuff from him in Masayf.
No big explanation or elaborate scenario is needed this time, I don't think, to reset your equipment levels for the new game.