The amount a Telecaster needs to be changed to avoid registered trademark violation is so slight as to be insignificant. They could also just change the r and the n in Fender around and sell Ferdens.
But everyone would know they were still Fenders.
If, however, all the "cool" guitar players suddenly began playing Parker Flys and Ibanez Jems ... Fender would go belly-up in a week.
Fender owe more of their success to their famous players than their guitar designs. And we're all sheep.
