I hear it's tween your current town and former. I agree, look at Garnett.
Garnett is a power forward, and that's why he's been able to play at least at a pretty good level into his mid 30's. Power forwards tend to have longer careers than shooting guards because they don't have to be as mobile. They just need to be able to hit a mid range jumper and post up.
Shooting guards are a completely different animal. They rely on elevation and quickness to create their own shot or get into the lane. Yeah, you can still be a spot up shooter in the latter years...but is that worth 15 mil a year? Look at mitch richmond, tmac, vince carter, michael finley, allen iverson,latrell spreewell, allan houston...just to name a few. i could probably find a bunch of other names that fit that bill.
their skills severely deteriorated in their early to mid 30's. There's a lot more jumping and wear and tear on their knees than a center or power forward. Michael Jordan was exceptionally lucky because he was extremely healthy for most of his career. That's incredibly rare. Kobe has had some minor procedures and minor injuries, but nothing like tearing an ACL or achilles or any type of serious knee or back injury
I wouldn't keep a shooting guard past the age of 32 or 33 at best. A power forward can play till they're 35 or so at a fairly high level.
Another guy i wouldn't want on my team for a 5-6 year contract is Amare. He recovered from micro fracture surgery and played at a high level, but he was a rare instance. There's no guarantee that his knee won't have further complications. He's a power forward that relies a lot on his agility and quickness to be a good player. Once he loses a step or two, he's going to suck. He's got 3 or 4 good years left in him. Look at what happened to kenyon martin...dude was a beast, then his knee went out, had microfracture surgery and he became a role player at best.
That's why Lebron, Bosh, and D-wade are by far the best catches. Still young, explosive and have no major reoccuring injuries (dwade had that one year he was injured, but clearly it hasn't effected him). They have 7-8 years of great basketball left in the tank