This is a tough one. Royal did add the Emerald Level and elevate the number of nights necessary to get into the Diamond tier; however, their continue to be this issue of too many people at that level. Honstly, the line should be proud with how many people they have in these upper tiers as it further demonstrates how great of a product they offer and a larger range of people continuing to sail with them.
I've got about 389 nights with the line, which places me in the upper tier (i.e., greater than 350) of Diamond Plus. If they were to remove access to the more formal Conceig. Lounge; I'd honestly be a bit pissed as it's always tough to become accustomed to a perk like this then have it taken away.
I also sailed on Brilliance during her crossing from London to Boston in September; and the Diamond lounge was opened up into the Viking Crown to accomodate for the overage of Diamond Members. Honestly, some sailings by their very nature are going to attract a higher tier level of folks than other sailings. I think the line has to understand this and makes for accomodations when this arises as best as they can.
As for a new tier level, I think it's coming and I think it's going to be breaking down Diamond Plus and Pinnacle into new tier sets. I think they probably are running into too many Pinnacles as well. Like everything, people will be upset and ultimately accept whatever they do as if you love cruising with them, a change in something like this won't deter your true loyal sailers (at least it wouldn't make me want to switch to a new line). Just my two cents.