Pocket Dogs Life Span

We know all about the small breeds but the pocket dogs are smaller than the chihuahua and the princess type shih-tzu, it is cute but is it advisable? So how about their life span, does this mean that it also becomes shorter? I am really curious about it because the trending of some breeders in breeding pocket dogs are becoming popular and even appeared on some local news abroad. And the top 5 pocket dogs includes the Yorkshire terrier, shih-tzu, chihuahua, Cavalier King Charles Spaniel and Maltese I hope that the standard sized dogs will stay because they are naturally like that.
Technology is really something you know, dogs are not like a Sony VAIO laptop that can be made into a pocket size just to fit the trends.

