Yes, hack will become outdated because game updates. And yes, sometimes (mostly) offset update is everything you need to get hack working again. For example, one hack is undetected for more then a YEAR. Only thing we need to update are offsets. If hack you have got some .ini file or .txt file where offsets are saved, you can mostly update it by yourself. VAC detection on other hand is something you can't fix if you don't have source.