Given the current framework, the only solution is to have more big investors, more sugar/oil daddies. The other solution is to change the framework in order to make the playing field more even. But that will be at the expense of the likes of Real, Barca, United, Bayern, Juventus...It's not realistic to happen. Football is huge business and radical changes of the framework are unlikely to happen.
Look, I get what you're saying and it's an interesting post, but think you're approaching it the wrong way.
To take your example of United and Arsenal, neither of those two clubs had had any recent success before they started to dominate. United hadn't won the league for 26 years before Fergie won his first title; Arsenal had only won three league titles in 27 years before Wenger claimed his first. It wasn't like they were dominating in perpetuity.
Why did they start to dominate? In United's case, they built a brilliant youth academy and sprinkled some high-quality bargains (Cantona, Schmeichel, Kanchelskis) on top. Arsenal bought some high-profile players but the real secret was their knowledge of the untapped French market. In neither case did they blow anyone out of the water financially.
Surely any club could have copied these models, right? But no, instead of pursuing long-term success the other big clubs (Newcastle, Leeds, Chelsea in the late 90s) threw money at big-name signings and got themselves into financial trouble. Money did nothing to improve their situation.
If you look at the other major leagues, it's true that one or two clubs tend to dominate. But money has only exacerbated that problem; just look at Milan when they were bankrolled by Berlusconi, or PSG under the Qatari regime. When one club has money, it's even less likely that a club like Monaco will burst through.
Even if a billionaire financier comes in and makes things more competitive, it's a bit of a fool's paradise. City have upset the established order but they've done so in a way that's totally contrary to the spirit of the competition. It's a bit like complaining about Usain Bolt's dominance of the 100m and proposing that all the other runners take steroids to close the gap.
It's still very much possible to challenge the elite without spending a fortune - just look at the CL final, and indeed the semi-finals. Look at Leicester and Atletico Madrid. If there were no sugar daddies in football these clubs would have more of a chance, not less.