[You're still useful in your own way, even if he wants you a bit dead. He also wanted to confirm something, he suspected Mary's 'kill' was a fake memory, especially as he'd seen nothing about it on the network.]

He just died with no warning.

I didn't get a chance to save his blood. This really could be it.

[Not that he had anywhere to contain it, either, but still.

Just in case you were wondering if he was still angry about the original experiment, House...if Sherlock doesn't come back, perma-killing would be confirmed...]