Even if dedicated servers could have a higher brick limit, the client still have to see those bricks.
To fix more problems on my idea, the client have the original limit on 128k bricks, but when it reaches it, it moves brick from RAM to HDD that is out of sight. If bricks are removed, it takes the closest brick and fetches it back from HDD to RAM. If some bricks come in sight, and others are out of sight, it makes the same swap as above.
When it saves, it takes bricks from both RAM and HDD and merges them together to the file it saves to. (Ouch for events and owners)
If you are no fancy of my idea, then you come with something better.