The 35-year-old Swiss admitted his return to Melbourne wasn't guaranteed after he ended a five-year wait for his 18th major title by beating Nadal in a thrilling five-setter.
He told the Rod Laver Arena crowd: "I hope to see you next year, but if not, then it was a wonderful year here and I couldn't be happier tonight." Federer has been rebutting suggestions of retirement for several years, but he said he was now aware injuries could force him off the scene.
The Australian Open marked his comeback from a six-month injury break, the longest of his career, after he underwent surgery for the first time last February. "This is all about, you know, knowing that I have only so much tennis left in me," he told reporters, when asked about the comment in his acceptance speech.
"If I do get injured, you know, maybe if I miss next year, who knows what happens... You never know when your next Grand Slam is going to be, if ever. You never know if you're going to have an opportunity at this stage."
Federer added: "Look, I've had a tough year last year. Three five-setters are not going to help. I just meant it the way I meant it. "There wasn't something planned behind it, that this is my last Australian Open. I hope can I come back, of course. That's my hope right now."
'Super-special' Federer, now four titles clear of Nadal and Pete Sampras on the all-time major-winners' list, was troubled by injury during the tournament and he said he had been carrying an upper leg problem since the second round.