Ya. But, to not use it at all because it might be ineffective in the future is foolish.
Just understand the escape mutant you end up with for non pandemic diseases in particular might NOT be the one you want to have.
The current circulating non-vaccine strain pertussis mutant has TEN TIMES the mortality and morbidity of the old one. Try for 100 next time?
You can vaccinate your 2m old and 4m old and every one else multiple times with the DTaP and still get the new one. And you'd better pray to whatever diety you worship your infant doesn't get the new one.
I'll quote the relevant line from the CDC abstract:
"Our results underline the importance of Ptx in transmission, suggest that vaccination may select for increased virulence, and indicate ways to control pertussis more effectively."