According to “Ideas” ,
You will not be forced to host your Mods on my Site or something like that, but it is highly recommended to do so for exposure reasons.
But as I know,there will be plenty of mods,with lots of space usages,so the server may unable to store them all.
Network is another problem.In my case,the maximum speed from https://gregtech.overminddl1.com/com/gregoriust/gregtech/gregtech_1.7.10/6.14.15/gregtech_1.7.10-6.14.15.jar is 150KB/s,and it will take 80 seconds to download a mod like GregTech6(Because of mini mods,it will actually take longer time).
For an open source game like Mechaenetia, some community-based mirror server might be a solution, but the IPV6 is not very widespread , and IPV4 is used up now. Put that aside,any computer can host some mods when running if wants. It need an big community, but in initial stage, hosting mods isn’t an serious problem.