With the new babies now I believe he will lose all of his stamina in long matches.I expect him to crash out more now then ever before.Once he starts to lose will see tanking and spraying even poor footwork.Tennis isn't his #1 priority anymore.That 15th slam was all he wanted this year everything else won't matter,#1,slams,titles,all irrelevant now.
Sounds more Like a wish than an expectation. No foundation for this whatsoever. Offcourse he does have a bigger chance of losing now than ever, he is getting older and more and more players seem to be able to challenge him. However it is a big step to say he is finished and I think it is ridiculous to say he has no stamina anymore, he played long matches against Roddick, Haas and Del Potro at Wimbledon and RG. He seemed fine there, this won't change over night.
I guess what you mean is that now that he has surpassed Sampras in slam wins and with the babies he is losing his drive. Well I don't think this will happen, only if he loses matches in the 3rd and 4th round of slams. That will take a couple of years.
Federer is very greedy you know, he wants all the slams for himself. This will not change now, he is only setting new goals for instance reaching 20 slam wins. Or winning 6 US open titles in total surpassing Sampras or winning 7 wimbledon titles equal to Sampras. There are enough records left and enough time to break them.