I don't see why you wouldn't just get one of the players that can play both formats? They're already hitting the market and with time I'm sure if one format doesn't come out clearly on top, the majority of players would be dual format (all of them support standard DVD and CDs so that's just assumed.
I personally like Blu-ray because it's not 50GB max on a disc, I think its 25GB per layer and they already have been testing discs with over 200GB, lemme check real quick.
Yep, 200GB - Read the August 31 update.
According to the Blu-ray Wiki Blu-ray discs hold 33GB per layer and can not only have multiple layers (6 33GB layers per side is the highest they've tested, that's TDK's 200GB disc) but can also be dual sided
so you could theoretically not only have 4 or 6 layers but have that many layers on each side, once they get a 6 layer, dual sided disc out you've got 400GB on a disc, though it'd probably cost more than a similarly sized hard drive