I think people would still consider ERC-20, taking in the consideration of its simplicity and ease, compared to building a completely new blockchain which takes more resources, time, and effort.
If creating a whole new platform will lead to solve the problem of scalability of ERC-20 then creating one completely is a good investment or invention to focus too. Though the non ERC-20 token might already have their ways to solve it but still did not attatin erc-20 popularity then users might still consider the typical process erc-20 serves that many still chooses it till now, even scalability issues arises.