IA needs an alternative - an independent backup archive - more than it needs funding. Unless IA funding exceeds the entire US copyright lobbying industry there is always a chance they will cease to exist without enough notice to save the data somewhere else.

There is also the matter what IA will be able to archive. The the machine learning gold rush more and more site operators see dollar bills in front of them and are restricting who can crawl their content. Google is in a special position here because almost no one can affort not to be crawled by Google which is what made their cache especially valuable in addition to the IA.