Prior to the actual merger of the NHL nad WHA in 1979, there was a proposed deal to unite the two leagues in time for the start of the 1977-78 season, in this plan not only were Edmonton, Winnipeg, Quebec and New England (Hartford) to be admitted but Cincinnati and Houston as well. This also would have meant that Wayne Gretzky would have played another year of junior hockey and entered the NHL draft in 1979. Unfortunately, Harrold Ballard and a couple other league hardliners vetoed the deal, much to the detriment of hockey in general.
So what would the NHL be like today if those 6 teams had joined the league two years before? Would Bobby Hull along with Ulf Nilsson and Anders Hedberg have maintained their elite status in the big league, would Gordie Howe have continued to rack up points against the superior competition? Its a question that has the potential to trickle down through all NHL history since.