The “communal tax” is an idea that has been floated around, of course there are lots of hole in it besides someones ability to pay , Would satmar be required to fund more modern Zionistic schools (and vice versa). What about conservative or reform jews in the same neighborhood, how do you get them to pay if they think yeshiva education is a waste (Some conservative and reform jews go to Orthodox synagogues).
The merger idea sounds good on paper, however the classes are already too large so you cannot merge the classes , You probably have to keep multiple buildings (no reductions on mortgage , utility costs and other adminstrative costs) and lastly there is the problem “Whose yeshiva is it” there are people who like to be in charge, Things like Hashghfa (some might seem minor hashghfic differenes but can be made into major issues)
I think when the idea of every jewish kid getting a jewish education first came out, they never thought of how to pay for it for the masses. Orhtodoxy was teetering so only the most dedicated went , there were smaller families so it was easier to pay. You will start seeing more dropouts (You already see some already) as families get poorer (THe high cost of real estate in NYC area doesnt help either), people will have to decdide to pay for expensive housing or yeshiva tuition) the problem is getting worse , not better