It's not going to happen. We will not see a new subsim for a long time, if ever.
Sub Sims were very popular in the early days of computer gaming because it could all be done in 2d. One by one every makers of subsims have dropped out or moved on to other genres. Ubisoft was the last one.
Any new player who comes in now will go into land combat or flight sims where there is more of a market. No one is interested in producing new subsims.
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