"Protected from Relegation"?

That should be a non-starter...at least long term. I could see certain assurances being given to certain teams that they won't be relegated for the first x years (I'd suggest 2-4), but to NEVER be relegated is a sham.

I posted about it before, but I still think there is a path for a 2-level, 4 conference, 8-division system. Based on geography. I linked a spreadsheet where I looked at this before.

64 teams in the top level/64 teams in the lower level
4 conferences of 32 teams (16 teams in the top level, 16 in the lower level)
2 divisions of 8 teams in each conference per level.

12 game regular season where each top level team plays:
1 team in the lower tier but part of its same conference/division
2 teams from any other conference of the top level
2 teams from the opposite division within its conference
7 games against the other 7 teams in its division

Regular season champs of each division within a conference play each other (conference championship)

That leaves four teams in the 'playoffs'.

Last place team in each division is relegated and the division champs from the lower division replace them.

Click here for link at https://docs.google.com/spreadsheets/d/1jl_V-9ZaOaP3v0kZfsnx