Riley should definitely get more than a year and first years should never be considered a true gauge of what coaches can do
As an example I will use Nick Saban
Alabama
2007: 7-6
2008: 12-2
LSU
2000: 8-4
2001: 10-3
2002: 8-5
2003: 13-1
That whole national championship thing that Saban had in his back pocket gave him a little more cache. Riley has never won a division at this level.
And Saban took over a dumpster fire, Riley did not.
Apples and hard boiled eggs.
Saban never won a national title before going to LSU. LSU and Alabama also had a ton of talent when Saban got there (more than we have now)
Before going to LSU Saban was 34-24-1 at Michigan State, take out his last year at MSU and Saban was 25-22-1. He was a very average coach at MSU with one good year.
I would argue that Riley took over a Nebraska team that was in a dumpster fire due to Bo's "us against the world" mentality that have permeated the team.
The main point I am making is that even a great coach like Saban struggled in his first year and while there are cause for concerns this year, the sky isn't falling. People need to give Riley more than 5 games before calling for his head.
I'm not saying that Riley is equal to Saban, just that not every coach automatically turns their team around in year 1. Don't forget that Saban lost to a mediocre ULM team at home in his first year at Bama. Give Riley at least a year to get his system in place and also weed out any bad apples that don't buy into that system. If we are regressing/not improving next year (or even toward the end of this year) the notion to make a change will be more valid.
Now is just not the time.