As of now you are the definitive TF2 YouTube creator, as you have the largest fanbase and the most constant upload schedule (mainly because of the new full time focus, congratulations by the way.) If we can expect videos daily, there is going to need to be more variety. TF2 is what made you big in the same way WoW made TotalBiscuit big. You could become a variety game channel like him, but there are more things that can and should be explored in TF2 itself. Someone else here expressed concern with how that TF2 likely wont be able to support the channel alone, and while he is right, there is far more TF2 content you can explore and showcase that is community made and also very high in quality. Namely maps and mods.
Skyrim is arguably the Mecca of PC Modding, with Nexus alone boasting a massive community with tens of thousands of files. For a community that big there are bound to be plenty of YouTubers who get popular by showcasing mods and demonstrating what they do in a more visual way. While TF2 is admittedly different, showcasing mods is something that nobody has really done before. Sure there are plenty of "Top 10 TF2 mods of all time!" videos on YouTube, but no real series that instead decides to showcase as many mods as desired over as much time as feels right. And because series are a thing you do, as do most full time YT producers, there potential for a new series unlike any other in TF2. A weekly showcase of mods. Now admittedly this can't be like MxR's Skyrim Mods Weekly, a showcase of the best mods of that week, because the TF2 modding community is not nearly active enough in the creation of content to provide enough for that to be done here. However a weekly or bi-weekly video that showcases a few of the best mods would be something that would shine light on a somewhat ignored side of the community.
Now while there are loads of stupid mods (reskinning health and ammo packs to Doritos and Mountain Dew or turning the Freedom Staff into a pimp cane) there are also a number of high quality game play enhancing mods that greatly improve the experience.
Paysus's First Person Animation Overhauls for Engineer, Sniper, Heavy, Scout, and Spy.
Kiyoshi's Reanimated FPS Animations:
Sniper, Demoman, Soldier, and Pyro
N-Cognito's Demo Primary Fixes: Triple Barrel LnL, 4 Barrel Stock and Rotating Iron Bomber
Spearmarshal's Beta Style Engineer Mix
Edracon's Gray Machine Team
And loads more. Tons of great mods are not known about by the community and a showcase series could be a new way to introduce more people to the improvements mods bring. Improvements that make an 8 year old game feel more current and up to speed, as well as fix issues the devs can't be bothered to change. That's not even mentioning maps. While STAR_ did occasionally showcase community map gameplay on his channel when he actually did TF2, nobody with an audience is putting a spotlight on community made maps anymore, which is unfortunate because there are many new ones getting no focus or coverage. That's a spot that can be filled by you. Be it weekly or biweekly a showcase of great community made mods and maps is something new and fresh that can add to the variety and uniqueness of your channel, and provide a spotlight for well made fan content at the same time.