Along with the Tomlinson cut, if we make the moves we are expected to (cut Uzomah, trade Zach), we will have over $31 mil in cap space. Where we can really win is if we can trade JFM. We'd be up to $38 mil of cap space, wouldn't really need to replace him because we could shift the linemen around and let McDonald play more. Plus we might get a mid to late-round draft pick for him. I don't think we'd get a high pick because he would have a fairly high salary for his new team to take on.
This isn't even considering the contract renegotiations, extensions and new deals that could open up a lot more space. Cap won't be a problem for the Jets, it's a matter of how aggressive they want to be at the expense of the future. Douglas has to decide how much he's willing to risk his future job security for current job security.