Assuming the feds don't do something really stupid....
Yes, you can expect the value to decline, as the asault rifle ban expires. Stands to reason, since now we can buy new.
If you trust the feds, sell now. Of course, if some bright feller suggests we extend the ban, then, it won't never go down in price, 'cause we still can't build any more.
If you understand this, you're a whole lot smarter than me.
Don't start no s**t and there won't be none, Terry