Never going to happen for many of the reasons already posted.
As for the CanAm series, it was dominated mostly by the Factory McLaren entries, however, when Jim Hall introduced his 'sucker' Chaparral the first 'restrictive' regulation was introduced in a series that initially had none.
The 'other' teams lobbied for this restriction for obvious reasons (money) only to find themselves under attack by Porsche and the 917 Turbo, which eventually resulted in the death of the CanAm.
Unlimited series (or is that Formula Libre?) generally fail through one manufacturer domination and little or no return on investment.
The pale shadow of CanAm that returned with envelope bodied F5000 cars was a farce and it too became a 'one make' series.