This is a patent infringement issue, similar to the one surrounding Plavix.
https://www.fhsc.com/news/ClinicalAlerts/CA_2006-09.pdf

If all the generics do go off the market, your insurance should switch back and pay for the brand. I do not believe a RECALL is in place however. Existing
supplies may still be available, for a short time.

As to effectiveness...this is very hard to predict. CPers really have specific
responses to things. I have read the most and heard the most confusing
claims over the years.

I can't predict what will happen for you, Liz. Perhaps nothing at all?
Sustained release products are dependent on the GI tract and speed of
transit thru can affect rates of absorption. Rates are allowed to vary according to the FDA within certain % limits, and faster dissolving products usually give a faster onset.
This is true with Watson vs Mallincrodt controversies. Watson's tabs are very soft, and M's are harder. So there are subjective perceptions of effect due to dissolution.

I am not working retail now, but our narcotic department at the facility where I do work does not have advance letters yet on this. This leads me to think existing amounts are enough to last for a while yet. Only the SALE is ended by Dec 31st by the company to wholesale distributors...all product sold before that can be used. As regions use the generic up, reports will come in
if any subjective effects are common. You might be lucky and get to see those.

It is all terribly confusing ..all the jockeying around. So I can understand you are concerned. If I hear anything, I'll PM you lickety split.