I did exactly this. rescued them and led them to sanctuary, did all Sturges's building quests, got sent to Tenpines Bluff, picked up "the First Step" from there, and never completed it. No settlement attacks, no radiant quests, just Sturges telling me that Preston would like to talk to me once in a while, but Preston doesn't initiate conversation, so I have not become the "General" yet or anything.
I have been building up settlements at my own pace and really enjoying the game.
However I am thinking that I may need to eventually talk to Preston/complete "The First Step" since I think you can't get "Old Guns"/Artillery without becoming the "General". Also, I may want to go with the minutemen ending, haven't decided yet.
In the mean time I am exploring and going through all the side quests.
Over 200 hrs in with this character and haven't discovered the institute yet, so not in a rush to talk with Preston.
I think if you're fine with not being a part of the minutemen, and choosing one of the other faction endings then you probably never need to talk to him at all.