I have a 2002 sportage - 4WD works fine thus far - car has even done some semi serious work - how likely are my hubs to become a problem

They will eventually go bad. It will be the vac hoses that will cause the problem. Kia fixed the hub seal part back in 1999/2000. You also need to make sure the front wheel bearings are adjusted properly at all times OR sometimes the new vac seal will also not hold the vac.

Overall they are OK for street use but for serious off road I would get the warn manual/OR automatic hub kit for your Kia. The guys on the board here have a lot of experience with the hubs. Do a search and you will find many posts.

I have a 2000 and as the rest of the pack, they eventually got sick. IN fact, they were already sick when I had bought the car in 2003 from the KIA dealer...and unknown to me at time of buy, the spring position had been reversed in the hub so they were in fact engaged full time. I quickly realised the shafts were turning all the time, diassembled the hubs, seen the problem, put the spring back in normal position and got good service during the summer. (In fact, the vacuum solenoid valve was dirty and sticky and would let vacuum seep through even when not asked for..so I had to correct that problem to get proper operation..and several have had this problem with the valve.)
QUestioning the dealer, they told me they had done the KIA recommended fix and the hubs would be changed free of charge when I want (car was still under original KIA warranty plus I had the standard used car warranty).. WHen winter came, they could definitely not be used and created all kinds of havoc...and Warn auto-mechanical with the KIA label were installed at no cost to me.
I have good service with the new ones but they have limitations in the way they must be engaged/dosengaged that the vacuum did not have..anyway, they work perfectly.
IN case it is of interest, installation instructions:
www.geocities.com/lmp4203/kiasport/hubinstall.pdf

Simple answer is they WILL fail. Change them now and save yourself a lot of trouble.

When the vac hub seals fail they draw a lot of water and dirt into the wheelbearing area, or of the hoses fail the water and dirt can seep into the hubs. Another possibility is the suction could draw water/dirt up into the intake manifold and into the cylinders (although that has not been reported).

Basically the vac hubs are <img src="/forums/images/graemlins/evil.gif" alt="" />, you are going to get left <img src="/forums/images/graemlins/confused.gif" alt="" /> as to why you are all of a sudden going nowhere. Change them now <img src="/forums/images/graemlins/kewl.gif" alt="" /> and say <img src="/forums/images/graemlins/nana.gif" alt="" /> to any possibility of <img src="/forums/images/graemlins/shiner.gif" alt="" />. You can then quite happily show people your <img src="/forums/images/graemlins/butwiggle.gif" alt="" /> as you go past them.

I was happy with the automatics as well 'till they failed me when I most needed them embarassing me. Now I have manuals and never again will I get a vehicle with automatics. By the way, I've seen many trucks stuck on trails because they have automatics and they failed as well, Chevys and Fords.