Recommend paying 10 years in advance. Then at the 5-8 year mark, do it again.

What scenarios are you thinking about to lose the domain? To me, the most common would be forget the pay the bill, or your credit card on file expires.

A light Google search tells me that it is possible with several different providers to pay for up to 10 years in advance. Still, the exact same issues can happen at the 10 years and 1 day mark! How do large corporations handle this problem? Do they have a special contract where the domain register will always keep the domain registered, then bill the corporation directly? That seems like a business venture with juicy margins.

I have the opposite problem. I want to get rid of email at a legacy unattractive domain but it's still appearing here and there so I keep paying for it and preserve the setup for it.

And that's the real hard part