I think building on Contentos after the mainnet is launched would be very interesting. I think the team should also focus on marketing. People need to know what going on in the ecosystem (investors and COS token holders as well). I think thats going to increase COS utility and market value.
I would advise against that though. That move should only be made after they have gotten enough fans not tied to the binance ecosystem.
Building on binance chain doesnt make Contentos tied to binance. Binance chain is a great blockchain, and it has some awesome projects on the chain. Contentos has a good number of things going well for them. I think the mainnet Launch would be a good boost for the project too.
I also share thesame views because building on Binance is still a mutual advantage for both COS and Binance. Besides COS seem to have to have alot of driving concepts which are inexhaustive. They should rather continue at that pace without reservations because they can always be new concepts to to implement