You're probably right, but there's no guarantee of that, and there hasn't quite been a case like Luongo's before. For one thing, unlike in every other case, LTIR doesn't really help his current team any more than him just straight retiring. Also, IIRC, in every situation that has occurred previously, the player was being LTIRed by the organization that had signed him to the deal or was dealt with him on or definitely going on LTIR, meaning the player was still part of a team he felt loyalty towards.
Luongo has no such loyalty to the Canucks at this time. It's not like things ended all that well there. He might frankly just decide to hang them up and be done. He's made over 95 million dollars already and his net worth is estimated near 50 million dollars, meaning that after taxes, we're talking like an extra 1% a year or so at best and less than that for each year he hangs on. It's almost at the not even worth it stage, if it isn't in fact already there.
Meanwhile, the Panthers cap penalty would be around 1 million if he retired this off-season, which in the grand scheme of things isn't a big deal, but if he were to retire a year or two after that it would be downright negligible (literally >80K or ZERO), meaning it frankly benefits the Panthers more to just let him retire and not have to deal with the hassle of having his caphit on the books to work around. It wouldn't even be impossible to LTIR him for one year, and then have him retire. That would probably be Florida's best option, cap-wise.
There's even a twisted option in which a Vancouver rival can make a trade for him, giving up a mid round pick, and then have him retire, particularly in a year or two, just to **** up the Canucks cap situation with minimal impact to their own cap situation. It's extremely unlikely just for reasons of decorum, but still completely possible.