In my opinion, MCGamer itself isn't going to die any time soon, as long as there are people who find the concept of "Minecraft Hunger Games" fun and come to try it out on this server, it will stay alive. What I believe is slowly dying is the bond that once made the community so special back then.
COMMUNITY WISE:
What I feel is that nowadays the community is split up due to the language barriers, (At least the EU ones, I don't know how the US and AU ones are doing) which makes it harder to interact with people, because most of the time the Turkish or Russian peoples level of English isn't great (Their level of education compared some other countries of the western world is lower), which creates small bubbles where people only interact with their fellow people of their language. This is seen a lot in clans where now where there are either only Russian speaking clans, Turkish speaking clans, sometimes Spanish clans. If you wanted the interact with them, most of the time you'd need to have knowledge in the language their speaking, otherwise it will be very uncomfortable and very awkward to try and have a conversation with these people, which is also why sometimes clan wars were a mess because people would have problems setting up the rules, and etc.
From my perspective, this is also the reason why hackers were such an issue back then (still is I guess, haven't experienced it in ages though), of course there's always these groups of people who come to the server and purposely trying to ruin others experience by hacking, but sometimes the fact that people did not know English and thus couldn't read the rules and know what's wrong and what's right to do on the servers, caused them to think that maybe it's not a bad thing here, which also created all these stereotypes of (All Russians hack, cyka blyat etc...)
This is something that we can't really do anything about it, we can't make the entire community to speak English on good level, but the only thing that is possible is to make the server more language friendly, translate the rules in Russian, Turkish and etc, we can hire more staff from these regions which can help a ton and explain them how the server and the rules work, this is where I actually believe the staff could create some bond between the community.
THE SERVERS GAMEMODE:
The problem that MCGamer has, is that it's really able to offer only 2 enjoyable game-mode: Survival Games and Survival Games solo, and that's it. The rest of the game modes that MCGamer can offer "can" be fun for a game or 2, but not as long as you'll MCSG.
I feel that that's the true weakness of MCGamer, it's ability to expand the server to its wider audience, if you're going to ask people what gamemode pups in their mind when they hear HiveMC or Hypixel, you'll hear a variety of choices, but if you'll ask someone from MCGamer, 99.99% it will be Survival Games, and that's a huge problem, when you take into account the amount of gamemodes it has.
If MCGamer wishes to expand, the only way it can do it is to add gamemodes that are PvP related: Factions (which they had), UHC, (I believe they had that as well?) and also bring Creative (Since it was actually played a lot, no idea why they removed it). Otherwise, it's only really a matter of time until the server will start bringing less traffic.
dam I wrote so much that I think I just completely ignored the question of the OP, oh well.