Nanopool is one of the biggest pools out there. They have been mining monero for a long time now and they EARN a lot from all the pool fees they collect. They will surely update and support the monero7 fork because it means money for them. I believe its only a matter of WHEN, not IF.
I'm very excited to see this fork coming, it's about time a good project stood up against Asics. My only question is when is this supposed to happen? First I heard early March now I'm hearing April 6?