Not sure about the ink smudging thing either. I worked with a right-handed Iraqi guy for a while who'd obviously learned to write right to left in Arabic, and I asked him if he had trouble smudging ink with a fountain pen. The issue had never occurred to him once in 55 years, so he grabbed the pen and wrote to see how he avoid it. He just arced his hand around the script automatically, no bother. So if right-handed Arabs can manage it, surely left handed Euros can too.
I used to play brass instruments, where you operate the valves with your right hand, then I took up the French horn which is the only one where you use the keys with your left hand. It took about a day to get used to it. I don't think it's that big of a deal. In the days of 16 bit home computers I taught myself to use the joystick with my left hand so I could hammer the fire button more quickly with my right - that became more natural after a while. Interesting that, because whilst I had just as much dexterity with either hand, I could never hammer the fire button as quickly with the left.
I went out with a leftie too, she taught herself to use a mouse with her right hand (without difficulty) because it was too much trouble to keep swapping them over at university computers. I also try to use tools with either hand too so I can switch when one gets tired.
I don't think it's as hard as all that to swap side, except possibly writing or other things requiring extreme dexterity.
Oh and whilst I am a true rightie, I instinctively get on a skateboard the goofy way round.