I don't know for sure if the songs will be re-arranged (á la Front Line Covers), but it seems like the most likely thing to happen. I'm also assuming they'll be tweaked at least a little, because if not for a little update, songs like FLY TO THE TOP and Ever stay snow will sound older than ancient. Besides, they'll probably want to edit the arrangements to fit the new vocals better.
I hope LSP will improve blossomdays. KOTOKO's version never really impressed me. On the other hand, I can't imagine them outdoing KOTOKO on Lilies line. I love the original so much.
And I'm also so excited to hear Kaorin sing Face of Fact and The Maze! She's done so few dark songs like this, it'll be nice to hear something different. Besides, they are great songs and I'm sure she won't let me down. I can already imagine her singing Face of Fact...