So my equally morbid presumption is that you mean before you're dead. Not too far from that myself. Not the dead part, I don't think, anyway ... the other one.
I think I'll just keep them and take them out to be admired and cleaned from time to time, I suppose. Unless and until I reach the point where I really need the money. I'm a good customer at a local mom 'n pop gunsmith/gun shop business and they're already sold a number of guns I didn't want or need on consignment for me, so I suppose I'll mostly go that route. Though I don't know what their expertise is wrt black powder muzzleloaders, so I might revisit that plan.
GB is a real pain in the you-know-what for the seller, unless you intend to get into selling multiple firearms, which these days is going to be pretty sketchy vis-a-vis the ATF if you sell and make a profit on your guns, and if you don't have an FFL, you might find yourself up on a felony charge.
I don't care what happens to them when I'm dead and gone. My estate can have the pleasures of dealing with that. Read: sarcasm.
So I guess base line my answer to your question is find yourself a reputable local gunsmith/gun shop, establish yourself as a repeat customer, and employ them to sell on consignment. If you just try to sell outright to a big-box sporting goods chain or to a pawn shop, you're only likely to realize 50% of current market value, whereas on a consignment you're more likely to realize 80% - 90%, depending on your agent's commission terms.