Yes no problem you can keep your coins there, and once the coins are received into a Segwit address, succeeding time they're spent or moved they'll be spent with all the features in Segwit. they'll be spent to any address once this happens. Segwit and paper addresses will move along side no problems, and it will not matter wherever they are from or where they are going to.
Can someone else confirm that there is no problem letting my BCH and BTC on a non-segwit address for a very long period?
thanks