Howard produced a heroic man-of-the-match performance against Belgium in the last-16 clash in Salvador on Tuesday but it could not prevent USA from bowing out of the World Cup following a 2-1 defeat in extra-time.
The 35-year-old broke the World Cup record for number of saves made in a single match, eclipsing the 13 set by Peru's Ramon Quiroga in 1978.
But, with Howard advancing in years, the 2018 World Cup in Russia may be a bridge too far for the 104-cap Everton veteran.
"What happens going forward with the national team, I don't know," Howard told reporters.
"Everything's a bit raw at the moment. I don't think it's black and white to be honest.
"There's no doubt barring injury that I'll be fit and willing to keep going, but there's a lot more things that go into that decision than just my physical health, so it's something that in time I'll decide on."
If the Everton shot-stopper, who signed a new four-year deal with the Premier League club in April, does not make it through to the next World Cup, he has already earmarked Aston Villa keeper Brad Guzan - capped 25 times - as the man to take his place.
"I would imagine at the moment the way things look, I think Brad Guzan," Howard said.
"He's a top Premier League goalkeeper, a dear friend and his talent is incredible."