All your ZEC stored within a T-address & Sapling Z-addresses can be transacted on the Zcash chain. The various wallet providers will have their own plans for adding support for Orchard U-address. And there will be a way to recover your ZEC as long as you secure your seed words(private keys) to your wallet.
The Zcash network is not deprecating support to any pool in this upgrade.
It would be good to know the recommendations around breaking down transaction amounts towards the migration flow for wallet developers to incorporate a similar, user-friendly experience.
Please post wallet related improvements & ideas here