A blue-ray add-on would be nice.
Advantages-
-Current 360 owners can easily experience HD movies at the fraction of the price of a stand-alone blue-ray player
-People can have the better console and still play blue-ray movies (slightly biased advantage lol)
-Competitiveness between an Xbox 360/blue-ray add-on and a PS3 will increase and eventually prices of either or both will decrease
-No more format war; all manufacturers can strictly focus on blue-ray thus bettering the technology as well as increasing competition and decreasing overall prices
-No more fanboy talk saying "well the ps3 can play blue-ray movies blah blah blah"
Disadvantages-
-blue-ray = sony = ewww
-With the format war being over, there's not much competition, so the price of blue-ray movies would stay the same
I'm sure there are other advantages/disadvantages.. but I'm on the -john- right now, so let me be.
These next few months should definitely be interesting.
P.S. I still need a 1080P T.V. argh!