After trying to catch up(probably missed quite a bit anyway) on the whole league stuff on which will be the new replacement, I think it's important to consider a lot of things.
First, I want to say that with ESEA ending its ties with TF2 as a league, this is possibly a great opportunity for the NA TF2 Community(or the whole TF2 community in general) to have a new beginning with a new league that can/will hopefully do better than ESEA during its run and perhaps even open up a chance to gain new players hopefully. Two important things to remember is: 1. What does the community really need? 2. Who can and is willing to provide it if possible?
I'd say #1 is highly important as it may ultimately lead to what people might choose to do, here's a short list of what I think the community could use in accordance with a new league:
A. A very organized, dedicated, knowledgeable, TRUSTWORTHY, and fantastic team that is highly likely to ensure good quality and not be questionable(as we known of in the past...)
B. Willing to communicate with the community and take them into consideration.
C. A very decent well-running functional website with a great UI in order to actually run the league and represent information.
D. Connections with a great production team/casters and of the sorts, kind of tied with A.
E. Multiple available decent servers with an actual working STV.
F. Willing to communicate with the community and take them into consideration.
G. Actual possible unity(the more unification there is, the better for games like TF2 and such).
H. Willingness to improve, as maybe they don't start out well at first or have X, but are willing to expand and provide it in the future.
There's probably a lot more, but do note I didn't list "LAN" or possible LAN. It's important to consider that you have to think about what's most important and I know that some leagues or people have this idea of trying to have a TF2 LAN or some eSports ideas involved and such, but there are also many people that are done/past that and just want to play the game, but hey you never know, maybe if we can first establish a good community-run league then there can always be plans for LAN in the future. Personally, I think it's more important to establish the most unified "go-to" league that has a lot of the aspects I mentioned and is more community-run, because a community can last longer in the long run than a different provider(ESEA, ESL, Faceit, or etc.) as you never know how long they might last or continue to support the game.
I haven't checked out all these new leagues that are popping up, their site UI, and what they can provide/do for the community, but one other important thing to consider is the players themselves and which league they decide to go with. We're still generally a small community with a limited number of possible teams. It is not good if a community as small as competitive TF2's splinters. An example, back then after tf2lobby ended, people were splintered between tf2center, tf2stadium, and tf2.gg for a small while, with all of them having great UI and potential, but just an unnecessary splinter. I'd think it'd be cooler if some groups/leagues collab, as someone mentioned having RGL+twiikuu team work together(which can be good as we lessen the # of possible splinters and can put more people working together to be able to handle providing the service).
Anyways, I hope in the end it all works out and the community be will be able to settle in a fine league run by a great team. Just remember to consider what the community really needs to survive and be able to have them play the game they love.