Once you find a good, reliable weapon, its difficult to use fully the other weapons in your arsenal.
Not sure if we have anything like Butler if he leaves, but I think there are a lot of receivers with a lot of talent. No Butler will just mean a different balance to get people open.
No Montgomery? If this happens, then I'm sure Breece Hall and Jirehl Brock will be a great tandem. And we still have a couple of upper class-men who haven't yet had the chance to be the feature back. After all, we didn't use Mike Warren this year, yet as a freshman he ran for over 1300 yards (why he got ZERO carries this year is still what I consider to be a huge failure on the part of Matt Campbell, but its his ball club).
Anyway, the point is that there is some great talent coming into the program (with perhaps some better O-Line play ~please!~). No need to panic in the absence of Butler and/or Montgomery.