I think there are some sound perspectives being offered on this, but I’ll add that the biggest thing to remember is that at the end of the day, you are your own business and as such, you need to make decisions from that perspective. I’ve worked at companies that I know had management that cared for its employees, but when times got back and the budget needed to be scaled back, made the business decision to lay people off. It wasn’t personal, it was business. I’d wager the company you currently work for would do the same if it needed to.
Same should go for you - when the time comes, two weeks notice is a perfectly professional and reasonable amount of time to give. If it would make you feel better, when you submit your resignation, offer to stay a little longer in order to help facilitate the transition. If they accept that offer, great. If not, at least you tried.