Doing some of my own reading, and research, I believe non-Segwit nodes are not "full nodes". The question for me now is, "How does this affect my cold storage coins contained in a legacy address?".
This is correct and this is because SegWit nodes can verify SegWit and non-SegWit transactions, while the legacy nodes can only verify legacy transactions.
But as you can see legacy transactions can be processed by both types of nodes, so the legacy addresses just "work" in the same way they always did. And I expect they always will.
Just think: if Satoshi will come into light in 10 more years and wants to access his Bitcoin, do you think that any developer can prohibit his access (if he has the keys) just because it's a legacy address??!
But IMO someday the developer and community might agree not to allow send Bitcoin to legacy address in future.
I'd not agree with such a decision. If I buy Bitcoin for long time storage (more than 3 years) I may want to use legacy address and I'd prefer nobody stops me.