Howdy, everyone, from beautiful Ontario. This news article from the Canadian Broadcasting Corporation is not exactly on topic, but I thought you all would enjoy it, as it is part of apple history in North America. Hallowe'en is coming up, and 60 years ago McIntosh apples were a typical Hallowe'en treat handed out to us kids, every year. The original McIntosh Apple farm is up for sale, and yes, there are trees on the property descended from the original McIntosh tree.
Replying a little bit, but very much not an expert because the property I was designing to work on was lost due to that Financial mess back in 2008.
As I studied the problem then, I talked to a very good Orchards man who said that what he does is buy and plant very hardy rootstock that survive well, that those get solidly set, and then grafts the new varieties he wants to try on to those root stocks, having cut away all of the original branches. Then in years following he kept the best choices by pruning out the kinds he did't like for whatever reasons he found best.
Once I have land some workable land again, I intend to try quite a few landrace/ permaculture orchard and garden - ish stuff, btw. Seeing as I have been planning my what I'm going to do for a decade now!