I guess financially it is not viable.
Funny thing is that Sport had an article about the new third division a week or so ago, saying how it was the envy of the rest of Europe and a huge success.
Anyways, there's opportunity in this. For example, if this is true, then a company could financially propose a new third division of 20 teams, which would certainly be easier to attract investment to.
Sure, you are cutting 20 teams from the pyramid, but I think 62 professional teams (20 Laliga, 22 LaLiga2, 20 New 3) is way more viable than 40 and a split group 3rd division which it seems, is struggling to attract investment, sponsorship and viewership.
Just hope it is a third party and not an adoption to LaLiga3 where there would be less trickle down with CVC already signed. Also so it would exist outside the Salary Cap and selfishly, would support development teams in Spain more like Barca B.