Consequences of rooting HTC One X?
Yes, most manufacturers (AFAIK including HTC, as I had this experience with my EVO 4G) will have the OTA update break if the device is rooted. This may have changed, but to my knowledge, OTA will not work after root.

However, devices can be unrooted, however, some are easier than others, and the process is different for most devices. Please note that most unrooting methods require a full wipe. Thus is the nature. 

However, if I can give you a bit of personal advice, custom ROMs can usually give you the features of an OTA update and much, much more ;)