I don't think anyone expects La Liga to become like an American sport where the league micromanages details to keep everyone competitive (though there is a reason NFL is so profitable, and it's also funny how the most capitalism-crazy country in the world runs their sports like communists - but that's a different topic); it's just not possible in football, where everything is so international. Absolute equality just doesn't work in football, you'd have to abolish promotion/relegation to give the league absolute control, and you'd be so detached from the rest of the world that you'd fade into irrelevance if you tried to bring in American-style equalizers like a cap and a draft.
It's not like the EPL is in good shape right now either, three clubs are clearly financially dominant there too. The Bundesliga is probably the most well rounded big league, but a lot of that has to do with the size and economic situation of Germany.
But something needs to be done. Revenue sharing is a start, there will still be haves and have-nots but it'll do a long way preventing clubs from imploding the way Depor, Celta, Betis, Alaves, Mallorca, etc etc etc. have.
The fact that the third and fourth most popular clubs in Spain (Valencia and Atletico) make as much in TV revenue as the bottom tier premier league clubs is telling. Granted Spain's economy being non-existent isn't helping the matter, though the fact that Barcelona and Madrid have never been healthier is telling.