Looking over 2k19 right now with no knowledge of the community, I'd say it is pretty saturated. Especially for when looking at it from a channel of your size.

2k20 is only going to be much worse. Especially for the first few months, and I assume this game ebbs and flows with the NBA season.

Being the best in the past is irrelevant now, unless you become one of the best in 2k20. Then this could be a large opportunity for you.

This is more a question about your mindset while streaming. If you are just hitting the "go live" button and having fun playing whatever. Then keep doing that? I assume you haven't been consistently or strategically streaming for 1 year to only have 70 followers.

So is this the moment now you want to be more strategic, more thoughtful? It just depends on what your goals are here. If you're happy with your Overwatch streaming, I imagine you'll have as much fun playing 2k20.