I don’t intend to migrate in the next few years. I would like to know if there will be a deadline for the discontinuation of the orchard.
I haven’t yet heard any discussion of that.
In my humble opinion, which a lot of other Zcashers strongly disagree with, the social expectation should be that you have to open your wallet at least once every year or so and connect it to the blockchain if you want your coins to remain first-class. If you don’t then the rest of us should start refusing to accept your coins at face value, and instead accept them only at a discount, ie a fee that you pay to the network to pay for the costs to everyone else of maintaining your old, unmaintained coins.
Here was a recent discussion about this: NU7 Sentiment Polling: Questions for Community Review & Coinholder Voting via Zodl - #33 by zooko