That's another idea, lots have been looked at and even the "golden goal" suden death in ET was tried for a few years.PKs to decide a winner is the worst. I would like to see keepers lose the option to handle the ball at the start of extra time.
The shootout is indeed a child of the 60'/70's, but it's not the "Cosmos" soccer league that is due any credit. You must be thinking of a novel tie-breaker they came up with, similar to the tie-breaker in ice hockey (I think).I think penalty shootouts was an American idea from the brief 1970s pro game back then, you know Pele et al. It is probably the least-worst system that works.