For me, Josh Anderson should not be a high trade price. Like you said 1 year away from a UFA. Yes he was injured last year, but how much can CBJ really ask for in a deal for a guy who scored 1 goal last year?
Then you have the other side of the risk, extending him past next year. So say the Bruins acquire him for a reasonable price, and he comes in an plays more like pre-injury Anderson (i.e. the 25-goal scoring version). Now he's going to want to get paid like you said. And someone will. Then say he's injured again the following year (2021-22) and he reverts back to 2019-20 Anderson. Then it basically becomes Matt Belesky all over again.
For me the only way I take Anderson is if CBJ moves him for a pretty cheap price, and they let him walk next off-season regardless of how he plays here. I see him as a pure rental. Pretty much zero interest here in committing to Josh Anderson long-term.