I mean could I implement zoomer and panner to the oscilloscope example plotter which won't have thread supported?
Sure, why not ?

I will have to much data to plot about 40 curves and each one could have 50.000 points. And Is zoomer, panner usage meaningful or not like this situation?
Depends on what you expect. Zooming or panning is always followed by a complete replot, what will be be very slow for 40 * 50000 points. But this is not different to the situation, when the plot widget is resized.

I strongly recommend to add different levels of detail to speed up your replot operation. Read this thread to understand, where to start.

Uwe