Jashon was not an explosive end when he first arrived and he'll remain firmly in the mix to start or be a regular contributor at DT next year, especially if Jones goes pro.
Right now the safe options at DT are:
1) Landers
2) Cornell
That's it. Sprinkle, Hill are gone. Dre'Mont might be, or could play end if needed for depth. Hamilton plays occasionally so he'll be there for depth but probably not big minutes.
they have loads of potential at the position , with a ton of young talent. I think Garrett and Jackson push for time.
They also have a lot of scheme versatility. If they can get another body or two at DE, they can sprinkle Young and Bosa inside on certain downs.
Brenton Cox was such a big loss. They'll be more than fine long term because Urban will close with someone, but they could have used his size for 2018.