Ryan Strome is on pace for 73 points. Yep, decent third liner.
I would offer Strome 5 years, $5-5.25 million AAV. Contract takes him through his age-31 season. Gets a nice raise, financial security, and the guarantee moving forward he plays with Panarin. If he wants a bit more, that's a bit dicey, but moving forward, at the very least, you know he produces between Panarin and Fast. The Rangers will likely try Kakko/Kravtsov in the top six during training camp.
Also, there is no rush to thrust Filip Chytil into a role he's not ready for yet. Let him man that third-line center spot for the next few years. At best, if he breaks through, they can trade Strome. At worst, if Chytil maintains this same level of production for the next few seasons, the Rangers can bridge him at a manageable salary cap hit and know they have a competent young talent who they can take their time with. The best case scenario is they develop Chytil slowly, and he breaks out in a big way during the bridge/RFA years. That means they will have a bargain on their hands, which is great for their salary cap situation.
This place irrationally hates Strome. He certainly isn't perfect, but he has been very good this season. He's been good since Gorton traded for him. Seems like the Rangers got very lucky a former 5th overall draft pick figured it out HERE. Not elsewhere.