Signing old guards, has not worked out for us in the past. Kemba did not.
I don't think we should sign him. No defense, his athletic ability will only worse with age. No man beats father time.
To be fair, Kemba may not have worked out so badly if the circumstances were different.
We signed Kemba at what seemed to be his prime age, at a time when we lacked a clear star player on our roster. As such we locked him in for max salary money over a long period of time, with the expectation that he would be our go-to offensive option.
He actually mostly delivered on that to begin with in year one, but then injuries broke him down and it all went to poop.
The difference right now is that we would not be signing Lillard for max money, and we wouldn't be signing him with the expectation of carrying a team. We already have clear leaders in Tatum and Brown. The assumption is that if we did bring in Lillard we would be paying him at most MLE money for a period of only 1-2 years. We would also be expecting him to be at most as #3 scoring option after Tatum and Brown...and would be fine with him being as low as a #5 option after Tatum, Brown, White and Pritchard.
If you only need Lillard to be a #4-#5 option, and you're only committing MLE money over a year or two, then that seems to me like a very low risk, high reward deal. He probably misses all of this season, then in year #2 if he doesn't deliver what you hope he will you simply dont extend him afterwards and let him walk. And if he does (by some chance) come back to anywhere close to his old self then you have yourself a huge win.
I don't see Lillard as the type of guy we would lean heavily on to carry the team. I see him as that extra wildcard option who you can go to every now and then when Tatum / Brown are having a bad night and just gives you a little extra offensive depth. Also when you are in the big moments at the end of key playoff games, and the defence stops you from getting the ball to Tatum/Brown, Lillard gives you another proven clutch shooter/scorer that you can run a play for and who can potentially deliver with a big shot.
In the clutch if you're an opposing team and you need to defend against a game winning shot, and you have Tatum/Brown/White/Lillard/Pritchard out on the floor, who do you leave open? Every one of those guys is deadly in the clutch.