I don't really believe that it is easy to trigger. The thread would have to be preempted at a very specific point for a very specific duration, the other thread(s) would need to perform exactly 2^16 operations within that time window and the final operation would need to trigger the ABA problem. Possible, but extremely unlikely. (In some applications even impossible.) Do you happen to have some real world examples?

But yes, it is definitely something to be aware of!

BTW, if the pointers are always aligned, the sequence number may have a few bits more.