I know this is highly optimistic, but I think we may be gearing up for the final years of "Cal Arts" cartoons in the 2020's, particularly if this Thundercats reboot bombs badly enough.
Steven Universe is nearing its end (assuming it hasn't ended already), Adventure Time is long gone and Teen Titans Go is a punchline that gets marathon runs solely because it does well with its target demographic and that's the key here...since Adventure Time died out, the one "Cal Arts" show that is doing well with its intended demographic is Teen Titans Go.
Steven Universe was popular for a while but has basically become the dangerhair equivalent of Rick & Morty in terms of how awful its fanbase is and actual children don't watch it.
IIRC, Gravity Falls ended a while back and I have no fucking idea how the She-Ra reboot on Netflix is doing, but I think that if this Thundercats reboot flops, it might kill the "Cal Arts" cartoon fad for a while. Especially now that Cartoon Network is under new management and Christina Miller is no longer in charge.
I don't know what will replace it as the new trend, but something will. Personally, I'd love to see action cartoons make a proper comeback, but sadly I don't think it's likely.