If I'm understanding your question. Playing EA on a club that does or doesn't have MLS Next at the younger ages (before MLSN starts) won't make much difference. When MLSN starts, clubs will be looking to fill out rosters and they won't prioritize kids from their own club, even if they tell you otherwise. Pathways are a myth.
Eh it's not a hard disagree but in my completely anecdotal experience of seeing teams being formed right at that transition to U13 level, they mix their A team and B team and standouts from the tryout pool and roughly 60% of the final team comes from A team, 20% from B team, 20% from tryout kids.
Again, totally just based on what I've seen or heard around me - at our current club and also just from friends family neighbors.