Wheel bearings ?

thanks for the dooms day outlook

they are not going to just lock up on, yes it is possible but for that to happen they would have to be so far gone you would know the bike was unsafe for along time, most likely you will just get a slightly wobbly tire and some noise, it will come on gradually and not all of a sudden, this said if you can aford to have it done while everthing is all apart you should as most of the cost is labor and not hardware

i have to disagree with you hagios
especially at high speeds its going to be hard to get it to just freeze up think how much force it would take to stop a wheel dead at that speed, more likely in a catastrophic failure it would be like you were breaking, or downshifting, you would definatly know something was wrong but unless you are hard into a corner you should be just fine