Just use some common sense here…
Why did MS put out a standalone HD-DVD drive for the 360? To sell more 360's. HD movie player capability is a selling point, especially when the competition is offering it.
They picked HD-DVD in competitive interest, and it was probably a cheaper choice, at least initially. Toshiba pulled the plug on HD-DVD, so now they can't claim realistic HD movie player capability as a selling point. The competition still offers it.
Is it suddenly not in their interest to offer HD movie player capability anymore? No. In fact, it may be even more valuable than ever since there is a single format remaining that consumers can get on board with without apprehension. There's no longer any reason for consumers to wait, other than cost.
Is there some reason that Sony would somehow prevent them or discourage them from offering a BD player with the 360? No. Sony has to sell them the technology just like every other hardware manufacturer out there in the world making BD players. If they in any way tried to gouge them, count on MS's team of lawyers to straighten things out as painfully as possible. It's in Sony's best interest to lower all costs involved as quickly as possible in order to speed up Blu-Ray market saturation in order to get royalties rolling in.
It's highly unlikely that MS won't produce an external BD player for the 360. More mysterious is "when" and "how much?"
With the stuff about it not being as updatable/upgradable because it's external…. That's not true. Same as an internal drive, an external drive just pulls raw data off a disk and sends it onward. MS can program the 360 to do whatever they want to within hardware processing limitations just like Sony can with the PS3. We will all have to wait and see how good a job they do with it. Most likely basic playback will be indistinguishable from other properly functioning BD players.
