The most future proof option is Gevenalle levers and shifters or the same levers with bar end shifters. I think microshift also makes 2x10 down tube shifters too. It looks like cassettes and chains in 10sp will be easy to find for a long time, though maybe not Dura Ace.
The above would work really well but neither would have the sexiness that you currently have.
In your position I’d get gevenalle. It actually might shift better than the original. I’ve been thoroughly impressed with Microshift shifters on a few bikes I’ve had.
Fortunately for me my sexy steel bike of the same age as yours has Campy Chorus. I got the levers rebuilt last summer.