It's just been revealed that Guitar Hero: Aerosmith won't support GH3 DLC. While I think that's a bad move, because it makes GH:A just a niche side-product, it got me thinking (a dangerous pasttime, I know).
We're starting to see the potential of DLC, how it can extend the life and interest of games for a long time. I think EA/Harmonix is the poster child for this. While I may not be interested in what they offer every week in Rock Band, I do keep an eye out to see what they are offering each week.
But how long should we expect this extra investment to carry? Is it reasonable to expect DLC to be forwards-compatible with future versions of the product? (Or new versions to be backwards-compatible with the DLC, however you want to look at it.)
I've seen the comment made (by myself included) that current Rock Band DLC should be compatible with Rock Band 2. But it could be impossible, depending on how different RB2 is from RB1. Just hypothetically speaking, if RB2, say, added a fifth instrument, and you had a five-person band, what would happen if you tried to play a set that included a RB1 song, which only has four instruments? Force one band member to sit out? Unless they re-encode all DLC to be RB2-compatible by adding the fifth instrument, it would be pretty pointless; and that's a lot of work I don't see any company willing to do for free for existing content.
Additionally, why would DLC for a specific game be treated any differently than the included content for that same game? Sure, if the content isn't compatible, I'm going to miss playing Boston's "More Than a Feeling" in RB2, but I'll also miss playing "Foreplay/Long Time". What would I reasonably expect Harmonix to do about that? They'd have to distribute all the RB1 content on the RB2 disc with all the new content, provide some way to hot-swap discs (or use the HD-DVD player to load both discs at once), install the RB1 content to the hard drive, or release the RB1 content as DLC — and that's assuming the content would even be compatible with whatever RB2 does.
I can see why Activision/Neversoft is getting a lot of flak about GH:A, seeing as how what they're releasing is essentially a content pack for an existing game (GH:A hasn't been advertising any big features or innovations over GH3). If Rock Band 2 turns out to be Rock Band 1.5 and has the same lack of compatibility, they'll deserve a lot of heat, too.
I think the reason that some of us hope for more is because the content is a little more personal. This is music many of us have grown up with and enjoyed, to which we have an emotional attachment. Having a chance to actually (pretend to) play those songs we used to just listen to is something we're hesitant to let go of.
But if Rock Band 2 has the innovation, I know I'll buy it. Of course, how much innovation is required to offset losing all the old songs is another question. I know of some must-haves, like online bands (although if you ask me, that should be a patch to the existing Rock Band), but I'm afraid that's more of a case of "I'll know it when I see it".