Get ready for $9M plus on a 6 to 8 year deal for him. He is the kind of player that some GMs will fall in love with and become convinced that he will be a great offensive defenseman for a long time. Heck - it might be over $10M. Look at the contract that San Jose signed Erik Karlsson to back in 2019 - it was $11.5M/year for 8 years. Turned out to be a terrible contract but it shows you what some teams will do when they are chasing the shiny new toy.
The Caps are actually pretty well positioned to do a long-term deal with Chychrun as they have a bunch of money freeing up after next year with both Carlson and Ovi's contracts finishing up. I love the guy, but I'm not sure how high I would want to go if it gets stupid.