Expanding the CL group games would just be even more unnecessary games, the same teams will still always end up in the last 16, which is when the real competition starts with the proper massive fixtures anyway. The epicness of the two-legged ties is what makes the Champions League so brilliant to watch, it's the greatest football competition in human history, it makes no sense to change it.
However, I can see why the big Euro clubs are concerned about the Premier League's rise. The reality is that we can sustain more big clubs and fund the smaller clubs to be more competitive in order to make it a better overall product.
The only way I'd ever accept a Super League would be if it had proper relegation and promotion to the National Leagues themselves. But as a Liverpool supporter and Premier League fan I'd obviously prefer shit to stay like it is.
The solution for the Europeans teams long term if trends continue and they fall behind elite Prem sides would be to group the French, Dutch and German leagues together, and the Italian, Spanish and Portugese leagues together. Then you'd have some seriously boss leagues.. Ajax fighting PSG, Bayern and Dortmund for one title, and Juve and the Milan clubs fighting Benfica, Real and Barca for the other. I'd be happy for us to take the Scottish clubs into the PL, Rangers and Celtic would be boss additions to the league.
This solution wouldn't be perfect, but I'd rather see something like that than an American-style Super League with permanent soulless "franchises" disconnected from the lower tiers of football.