To clarify, the proposal is to just deprecate the package in Fedora, by the policy this means just that newly added packages cannot depend on it, but it doesn’t immediately harm any existing package.
@yselkowitz this article suggested by @churchyard shows some example dateutil replacement cases, but it’s hard to cover every usage.
As said in the proposal, I’ll start looking at fixing the FTB with Python 3.15 and I hope this turns out to be simple. If not, we’ll soon have a big problem, since a unbuildable dateutil will result in a massive failure in the entire Python ecosystem.