I would be extremely surprised if Porsche would be so reckless with an immediate facelift.
I think they are pretty good at marketing and you don't need to be an expert to understand how pissed off your client based would be with a new car already getting "old".
It just doesn't make sense.
I'm a lucky owner of the first customized 991 Turbo S delivered in my city and I feel quite comfortable that it won't get old too soon (maybe I'm just an optimist ;)))
 
RC I'm finding that, even with winter tires, the skid effect is quite important on cold wet ground. Don't you?