All 7 from the top 4 richest football nations and it would be very surprising if anyone out with those 7 teams wins it again, if it happens it will be for one of two reasons, a club finds itself a billionaire or a complete fluke. The fact that barca have won four of the last 10 means it is predictable.
There was a time when European premier competition could be won by a much much larger pool of teams, it had prestige and it was a novelty, now that pool of teams is down to about 8 at most. The group stages are a massive borefest because the outcome of each group is more or less set because of seedlings. Sure you might get the odd victory for the likes of Celtic winning against barca but ultimately Celtic go out and barca will progress to the latter stages.
Even the last 16 is quite boring, the last 8 is where it gets quite intense because the super rich clubs finally have a challenge from another super rich club. These super clubs have the best talent in the world which means the "pretty" football they play will continue to attract the arm chair fan even though most of the games screened are pish.
With these clubs getting stronger and stronger every year they will only ever have the odd year of transition till they return to the top of the European tree. Unless there is an overhaul of the European cup we will see the same super clubs dominate this competition whilst domestic tournaments are devalued.
As for your comment on domestic leagues being predictable, well it's for the same reasons as above, the super rich clubs dominate because of their vast wealth compared with the rest of their leagues, where do they get that vast wealth.......the champions league and its TV money. Just because leagues are now all as predictable as each other does not make it right. At least Scotland was first at something, we were the first to allow such a gap to be created between a couple of big clubs and the rest.........although it's just one club now.