The most likely kind of 'unworkable' is H-bombs degrading into 'small' fission weapons due to lack of maintenance (tritium needs periodic replacement). But 'small' in that context means 'like the weapons used on Japan at the close of WWII'.
The delivery vehicles may or may not be toast. I'd expect liquid fueled rockets to be degraded - but they pretty much didn't / don't have those as they're problematic with mobile launchers.
TL;DR: a smaller threat, but not something I'd be sanguine about.