NFL executive vice-president Mark Waller says it remains "realistic" for an NFL team to make a permanent move to London in the next five years.
London will host its final International Series game of the season on Sunday when the winless Cleveland Browns take on the Minnesota Vikings at Twickenham.
That will mark the 21st regular season game played in London since 2007 and talk about a franchise being based in London has been constant since that first match a decade ago.
Waller visited Sky Sports News on Wednesday and said: "It's still definitely my aim as the one responsible for developing the fandom here. And I think it is realistic.
"That sort of timing would align with the next collective bargaining agreement so if we were ever to put a team here that would need to be agreed with the Union.
"It also coincides with the renegotiation of our broadcast agreements and obviously if we were to have a team here we'd have a very different broadcast agreement in the UK, and so the timing feels right from a planning perspective. The fan growth feels definitely right and all of the indicators are very positive for us.
"The main thing that teams worry about, and the owners worry about is, if that was my team and I was the London franchise, would I be able to be competitive week in, week out, year in year out.
"Also, would I be able to attract the top talent. Those are the two issues we are spending most of our time on at the moment in terms of how we would manage that."
Most players and coaches who have visited London to play have left with positive thoughts, although Baltimore Ravens coach John Harbaugh admitted his team's visit this season - which ended in a heavy defeat by Jacksonville - had caused a disruption in their routine.
Waller added: "It's obviously a different routine and I think the fact that he was on the receiving end of a quite sharp defeat probably didn't help his sentiments as he left to go back to the States.
"I actually followed up with the club president and he identified three things - time zone changes, travel disruptions and traffic around London were the things that irritated him. Not much we can do about traffic but we have a good handle on the others. Ultimately I think we've had 19 teams and I think two coaches have commented unfavourably."
Twickenham will be hosting a third NFL game - the rest have been at Wembley - on Sunday but Waller said it could be the last for now, with the new White Hart Lane scheduled to become London's second NFL stadium when it is completed next year.
He added: "It's highly unlikely we would use three stadiums, and we have contracts with Wembley and Tottenham for next year. However we'll have to see if the Tottenham stadium is ready. I don't want Twickenham to be seen as a fall back, but it's a contingency."