Our real period of dominance is yet to come and may not be as far as some imagine. For the past 10 years we've either been in the mix to win something & have done so or we were miles off. A real elite club may not win the league every season but puts up a challenge right to the end and gets within a couple points of the leader, not 20 points behind, or getting rolled over by relegated Wigan because they had a bit of a tiff with the manager. You often hear how great it is that the likes of Silva, Kompany, Aguero never rocked the boat to go to Real Madrid/Barcelona when maybe they had the ability to, but there would be a lot more scrutiny on players who go missing in action like the last Mancini season and Pellegrini season 2 & 3. You see that now with Hazard at Madrid, taking every second season off was acceptable at Chelsea as he was by far their most talented player, can't get away with it so much now.
I wouldn't be as worried as some about losing the core of the successful sides since takeover, there are a number of recent examples of teams that add 3-4 of the right players & maybe a change of manager to look a completely different side. Bayern looked a shambles and years off being the best in Europe a few months ago, of course you still have to get your decisions/transfers right. We've been piggybacking off these players but now we're one of the best clubs to be a part of and absolutely nobody is doing us a favour by managing/ playing for us. Just have to make it count