That's like playing Russian roulette with your capital. If at any time you legitimately try to spend capital that has never been declared, you have some explaining to do about how you got it and why you didn't declare it.

If you haven't used your coins in any way, and that for years, you could say that you miraculously gained back access to your private keys, but you'll be subject to tax from that point.

In all cases you will end up paying tax, unless you just want to get high on your massive on paper wealth that you won't ever be able to spend or use in a legal way. Things aren't easy for people fitting in that category.