I've often thought that the big 3, 4, 5, 6 or whatever they are in any given year should be encouraged to join a Euro Super League, but knowing that if they do that there is no fallback position for them in the English League. As pointed out elsewhere the supporters of all the likely teams in a Euro League expect to win week in week out, so for some it would be a rude awakening and test the support of their plastic fans.
While it might take a while for English football to reshape without the big 6, a more even contest could galvanize domestic football and retain a global interest whereby it could still hold its own. If it were to ever pan out this way I'd envisage it wouldn't be long before a few of those big 6 were begging to come back into the English League.
What I definitely don't want to see are the big 6 maintaining a foothold in both camps by playing teams in a European League & our domestic league. The remaining football clubs will need to stand strong against that ever happening.