While the twitter banner updates certainly are nice, there is a glimmer of hope that Valve will show some love to TF2 in the form of "Team Comtress 2", which is a community-driven fix-up of TF2's code, including performance, UI, QoL improvements etc, based on the leaked Jungle Inferno source code.
The hope is that this is presented or brought to the attention of Valve and they will be able to verify and insert fixes and changes from it to the main game (it's not a replacement as again, it's based on the old source code from roughly 3 years ago), especially given the recent Last Stand update brought to L4D2, which was done in a similar fashion by the community.
The reason Valve are impressed with TF right now is because this Halloween update statistically brought more players into the game than it had ever reached since SteamDB started tracking playcounts years ago.