AFL chief executive Andrew Demetriou has hinted that the competition's extension to 18 teams over the next few seasons could mean the final eight becomes a final nine or ten.

The AFL has used a final eight system since 1994 when the league had just 15 teams, but the forthcoming introduction of sides from the Gold Coast and Greater Western Sydney has forced the league to consider alternatives.

However, despite hinting at a possible five week finals series and a longer regular campaign, Demetriou said there would always be some form of pre-season competition on his watch, regardless of the mounting criticism against the NAB Cup.

"There will actually be a bye next year, we are doing work whether it will be 22, 23 or 24-week season," Demetriou said in Perth on Friday.

"(But) what do the finals look like? Do we still have a final eight?"

"We have a top-eight of 16 teams which is 50 per cent of the competitions. When you go to 18 teams, someone could argue why we have not got a top nine."

"There is no reason why we cannot have a top-nine, and someone sent me a proposal the other day suggesting a top ten."

"We will look at all those things, and we would be remiss not to canvas all those options."

"They are all options we are looking at, and I promise you we have not come with a definitive solution yet."

"There are pros and cons in all that. Our guys are doing a mountain of work … hopefully (it will be worked out) by mid-year and towards August and September we will have a better feel."

Although both St Kilda and the Western Bulldogs appear to be taking Saturday's NAB Cup final seriously, the pre-season competition's glamour has certainly worn off.

Former Essendon skipper Matthew Lloyd became the latest in a long line of people to call for the competition to be scrapped this week, particularly with a longer regular season appearing on the cards.

But Demetriou refused to entertain the possibility.

"I think Matthew's entitled to his opinion," Demetrious said. "But every club tells us they need preparation to get these elite athletes ready for the season. They just can't throw them into round one."

I can assure you that ... if we didn't have a NAB Cup competition, particularly a NAB Regional Challenge, it would be to the detriment of the preparation of the players."

"We get to showcase the game, we allow people around the country to touch their players and connect to their teams that they wouldn't normally see."

"Not having a NAB Cup or Regional Challenge would provide four or five weeks of no football coverage and as other codes elongate their seasons, we actually want football to be talked about."