Seahawksdraftblog.com has the following about re-signing Richardson next year if he works out as a fit here.
"According to Spotrac, the Seahawks have an estimated $26m in free cap space in 2018. Spotrac’s numbers work under the assumption the cap increases to $168m next year, a miserly $1m increase on the 2017 total.
Here’s how the cap has increased in recent years:
2017 — $168m
2016 — $155m
2015 — $143m
2014 — $133m
2013 — $123m
Considering the average growth per year since 2013 is $11.25m a year, the chances of it only growing $1m to $168m in 2018 seems unlikely.
So basically, there’s every chance the Seahawks will have comfortably more than $26m in cap space at the end of the season.
Cutting or trading Jeremy Lane in the off-season creates another $5m. Cutting Neiko Thorpe creates another $2m and it’s the same for Jon Ryan. So there are plenty of moves they can make to further bolster their available cash if required — even though they might not need to.
If Spotrac’s numbers are accurate and if the cap continues to increase, they could have upwards of $30-$40m to spend.
Over the Cap has the same point of view."
http://seahawksdraftblog.com/