Trademarks rights must be maintained through actual lawful use of the trademark. These rights will cease if a mark is not actively used for a period of time, normally 5 years in most jurisdictions
Exactly what does "actual lawful use of the trademark" mean, and how much is necessary?
Would the law firm's claims hold up in court?
A similar example from reality, not part of the question
In Norway, the snack company Maarud had the trademark for the word "Potetgull", which was supposed to be the norwegian word for "potato chips". The word eventually over the years got that exact meaning, with people no longer associating it with Maarud, but potato chips in general. When a rivaling company, KiMs, released potato chips with the name "Potetgull". Maarud sued KiMs and lost because the word had fallen into everyday language