AFAIK, it's the law. It covers just about everything. Manufacturers are not
allowed to immediately "abandon" discontinued products.

Cite what law requires this. While it may seem like a fine idea I seriously
doubt there's legislation worded to require it.

I posted an answer at least a week ago.

It appears there is no Federal law, but many states require manufacturers to at
least provide some "satisfactory" solution to service problems for a period of
time after a product is discontinued.