They're never going to be far enough in the lead, they had a first mover advantage a couple years ago but the gap is never going to be that large again.
Once a major player just decides "ok we're going ads for free users" the rest of the industry will follow and have an easier time doing so.
I think if they wanted to do this they should have just taken the flack, free users of the product are a drain and they can't cave to them. Eventually free users will "get over it" and if OpenAI opens the ads flood-gate then all the other free-to-use LLMs will be ads based as well and non-paying users won't have an ads-free place to go.