TL;DR: Make Valve Competitive more accessible to Casual Players, but also interesting enough for the occasional community comp player.
1) Remove Fixed Settings
2) Class Limit 2
3) 5CP, KOTH, Payload w/ frequent map rotations
4) Medics get more MMR on win and less on loss
With any one or all of these, I think we can move Valve comp into a 'midway zone' between casual and third-party competitive. VC should never seek to replace community competitive, its way too late for that but by providing a place where casual players can get a taste for organized play as well as competitive players having a more relaxed way to play TF2 without the chaos of Pubs. It doesn't make community competitive easier to play but makes the road to get there FAR easier than it is now.
Removing Fixed Settings does risk giving people certain advantages but the benefits far outweigh that risk. It would make sense for them to do that in newer games but the game is too old and clunky for Fixed Settings to be a thing. Class Limit 2 is a happy medium between the more restrictive community competitive and the unregulated casual. Frequent map rotations of a core set of competitive maps from 5CP, to KOTH & Payload means different classes and loadouts become more effective, meaning room to experiment and develop gamesense faster than just grinding one class for hundreds of hours. Medic is a problematic class as it is necessary to win games but noone wants to play them so providing some sort of incentive such as easier climbing of the ladder or a 'Medic Bonus' that gives a small increase in MMR victories for subsequent matches may help people play Medic more often in games.
This is just my thoughts, but using Valve competitive as a natural stepping stone to more professional play then we could see more engagement in both competitors and viewership on streams. And who knows, perhaps by playing Valve comp even we may find new strategies or playstyles.