First off, let's assess the purpose of this question. If you're implying that an argument against a system is invalid without a fully thought out proposal to replace it, you're engaging in pointless sophistry. If someone says "I think my leg is broken" you don't ask them to tell you exactly how they think it should be fixed before you believe them. We don't have to know the solution in order to realise we have a problem.

With that caveat out of the way, I'm personally a big advocate for getting private capital out of rental markets. I know a lot of people just want to eliminate renting altogether, but I agree that this is short sighted. It either relies on the idea that everyone owns their home, which isn't always practical, or that people simply have homes provided at no cost, which opens up its own complications. Basically, while I am in favour of the total destruction of capitalism, I don't think that has to mean getting rid of money. Money is a very useful way of tokenising resources so that they can easily be exchanged. This allows for more efficient distribution of the correct resources to the people who most need them.

What I want to see is rentals at a price that everyone can afford l. Obviously, in an ideal scenario this would be paired with UBI to ensure that no one ever goes unhoused, but we'll focus on the housing side for now.

If given total power over my country's political system, I would look to implement a scheme that would ultimately result in rentals being handled only by Crown corporations (not-for-profit entities operating at arm's length from the government) created with a mandate to provide affordable rental properties. These corporations would invest building and buying housing in their area in order to fulfill this mandate. They would also be required to offer rent to own schemes. Rental rates would be set by a formula that would account for factors affecting the desirability of a property such as location, square footage and amenities. Conflicts would be solved by waiting lists.

Private rentals would be outlawed (with possible carve-outs for situations like a property owner who is temporarily away from their primary residence - even in these situations, the rental would be handled by the Crown corp with the collected rents passing to the property owner, minus a handling fee). Most likely this scheme would be phased in over time, allowing investment property owners to sell off their properties to the Crown corps. Investors would take a hit on this, but any economic downsides will be more than offset by the upside of the vast majority of the populace becoming, in effect, significantly wealthier (in GDP terms the economy would certainly shrink, but GDP is a terrible measure of economic health).

Unfortunately necessary disclaimer: This is the rough outline of a proposal. Were I actually in a position to implement it, a LOT of details would be worked out in committee, with advice from respected experts. This disclaimer shall be henceforth known as "The Sign". Do not make me tap "The Sign."