Just because something is covered by a TSB, does not mean that Ford will pay to repair it after the vehicle warranty expires.
If the dealer supports you, you sometimes can get so-called goodwill money to cover part or all of the cost of the repair. I had that for several TSB-related items on my 1992 Explorer, including the exhaust system and engine head gaskets. Ford refused to cover my rusted-through quarter panels, but it DID offer me $2,000 off a new Explorer (after I complained to various executive offices - I have not bought a new Explorers, however.)
One interesting thing to consider is whether some TSBs can be viewed as evidence of a defect that could, in some states, lead to a breach of warranty claim under the implied warranty provisions of the uniform commercial code. Some states do not permit manufacturers or retailers to disclaim the implied warranty. And while some states fix the duration of implied warranty to fives years, others, such as Connecticut, do not allow any time limits. I'd conclude, therefore, that, no matter how old the vehicle is, one might have a cause of action if it can be proven that the defect came with the vehicle when new.
I've often thought, for example, that owners of 91-93 models with rusted quarter panels (I just had mine fixed - $1,300) should consider a class-action suit, citing the FORD TSB that acknowledges the defect.
As far as safety-related issues, those are covered.