yea thats the simple answer, any ninja can learn ALMOST any technique, excluding bloodline limits,jinchuuriki techniques, and the ones that come from thereof.
Its just a matter of time and training. But why would you go through the trouble of learning one style all yor life(even if you HAD to) then switch to another, and be a complete novice at it for years.
its like a pro skateboarder just deciding to learn to roller skate, sure he CAN, but why suck at sumthing else when he's really good at what he's already doing.
"Knowing is not enough, we must apply.
Willing is not enough, we must do."
- Bruce lee