I kind of agree that it's hard to be hyped, for several reasons. For one, the price of the (almost) complete set is literally the same as the console. That wouldn't be a problem if I knew Rock Band 4 would give me as much enjoyment as Rock Band 3. But I don't.
I don't know what songs to expect. Probably, if the game gets its act together, we'll get a mix of old and new rock stuff. The thing is, I didn't hop onboard until The Beatles and what really made me enjoy RB3 was all the music that was partly influenced by the existence of the keyboard. Like, I doubt we'd get as much Billy Joel and Queen is there hadn't been a keyboard to take advantage of the variety in their songs. Now instead, I doubt there will be much of the piano rock I like, and if there is, I'll be annoyed that it will won't be playable on keyboard anyway.
I also don't know if _all_ my DLC will work, and if it will work from day one or be added haphazardly like the (frankly poorly managed) Singstar library. I don't have many RBN songs so that's not an issue. I do know that Bohemian Rhapsody won't be available and that _is_ the very top song that my group always wants to play. I don't want to spend $300 on RB4 only to have people ask me to put RB3 back in.
Finally, I don't know if my old instruments will work. The drums are dying either way and I'll be glad to replace them, but, especially since distribution might be sketchy, I'm hoping to use the PS3 Guitar Hero 4 guitar as a bass and maybe the Singstar mics as harmony mics. Will this even work?