It's hard to answer what you're asking in regards of "will tf.tv prepare for MM" or that we need to "prepare". You seem to think that this preparation is being able to help new players out, so it's hard to say. In CSGO, new players or players would generally youtube or google up guides and help(such as warowl you stated) to learn. I guess it would be the same for TF2 as tons of people with great tf2 helping content such as SLIN or other popular TF2 youtube channels will do the same. As for TF.TV's role, this site/forums has always been somewhat of a good central place for competitive TF2, but remember that most of the people that go here are already experienced TF2ers/ESEA and a decent amount that aren't those people are here to ask questions and etc.
I think one thing that could happen is TF2 youtubers like Slin and others that make guides or help new players tell them a little about TF.TV to direct them here if they have any questions concerning configs, hardware, or tf2 in general. Maybe it's possible(but maybe won't be as organized?) if we open a subforum meant for new players that need help and we have it on the front page saying "New player? Click here to ask for help!" and they can make threads on any questions they have. The bad thing is that it may make other subforums like TF2 General Discussion or Q/A Help not used anymore. Or we could have the front page say "New player? Click one of these that suits your needs" and it could direct link them to the correct subforum. Overall, I think TF.TV will do well for when MM comes out, it can adapt easily.
It'd be amazing though to see a big TF2 mega video over basic settings that need/could be used(like hitsounds and dmg numbers), concepts and basics of comp TF2 in 6v6 and highlander), available sites/resources that the TF2 community has to offer, and etc. Something like how Purge has his own "Welcome to Dota, you suck" guide for Dota 2., something new players can watch and learn a lot from.