UEFA is going to
change the seeding rules for the Champions League next year. Instead of the eight teams with the highest UEFA coefficients, Pot 1 will consist of the winners of the seven biggest leagues (currently England, Spain, Germany, Italy, France, Portugal, and Russia) and the previous years UCL champion. Its not yet clear what happens if, as is likely to happen relatively frequently, the previous years' champion is also a league winner.
The big winners are clubs like Zenit/CSKA, Juventus/Roma, and Porto/Benfica, who will get into Pot 1 by winning their national competitions. Some of these teams - especially the Portuguese ones - currently have high UEFA rankings anyway, largely due to their recent performance in the Europe League. But those rankings were probably not sustainable in the long run so having an auto-entry into Pot 1 is a boon.
The big losers here are clubs in England and Spain, which had been accustomed to having at least two and often three spots in Pot 1. A club like Arsenal would seem to be the biggest loser, given its longtime standing in Pot 1 without having won the league, but Arsenal were quite likely to drop out of Pot 1 anyway next year. Clubs like City and (when they return to the competition) United might be short term beneficiaries, given that their current UEFA coefficients aren't good enough for Pot 1 anyway, but still long term losers.