Sorry, but i think this is not a good idea at all.
Small note before starting, what you are describing is not pure survival, pure survival would be what people call "anarchy servers".
If cubecraft were to implement this, the server resources needed to pull this off would be way too big.
(Minigame networks work so well becuase you can have hundreds or even thousands of smaller servers (or mini servers) running at once, since every same is separated, and you have at most 40 people in a single mini server. Minecraft (at least java edition) was not made for more than 50 people online in the same server, because minecraft cannot be parallelized easily, so you need a lot of single-thread power, and the best processor for that task is expensive and not even then able to run 300 players online without lag).
To pull this off cubecraft would have to choose one
(or a mix) of three options:
- A very small player cap,
- A lot of lag (like A LOT, just look at anarchy servers),
- Have to split up the survival into serveral smaller servers and different worlds, but that would make it boring, imagine cubecraft split survival into 4 smaller servers, server 1,2,3,4, and you started out in server 1 but your friend plays in server 3. You would need to start all over in your friend's server. This would also split the survival community.
The compromises that would be needed to make survival possible simply are way too many, in my opinion, and would create another thing for developers to put precious time into, time that could be spent fixing or making existing games better.