Yes, it is very possible the picture tube is simply gone.
The tv however, needs the crt drive and other voltages checked to
confirm the problem.
Q5104 is a common failure transistor on some models of Zenith sets at
the end of the picture tube problem. It goes leaky and will check good
on a meter, but the voltages will be all wrong.

Since the focus is out, I am betting on the picture tube.