Ever onwards I say. Their older sound isn't challenging for them to write, so they've stated. And honestly, across HT and Meteora there are 20 odd songs that do the same thing, cover the same ground, use the same formula. There's no point in continuing to do it.
FYI, Blackbirds is a leftover track from Minutes To Midnight that they finished off for 8-bit Rebellion, it's not an indication of what the new album will sound like. Just in case anyone thought otherwise...
For me, as long as i can find a LP feel to it, its a good LP song. I mean, what defines a band isnt only its first album right? In M2M, even though it was different from their older stuff, i could still see the LP in there. it wasnt as though they'd given up what they stood for from the start. Their songs had the same meanings and still made for a good listen. Same with blackbirds... I guess for me, as long as LP doesnt change their own definition in their songs, them trying out new direction is fine... (but as a PS, i liked their fast paced songs better too... not to mention ones in which Mike's rapping takes a stronger stand, but then again, that's just my taste <.< )
If Linkin park went back to the 'classic' sound, they wouldn't be inspired or satisfied being stuck in the 'nu metal' pigeon hole. Minutes to Midnight was inevitable. From the interviews I've watched and read, Linkin Park decided to switch it up because their formula was becoming monotonous. Besides, I don't see what other directions Linkin Park could have taken in a fourth record if they stayed 'nu metal'. Every song, every album that Linkin Park does has its own unique sound to it. If they became one of those repetitive bands, it would be a real shame.