There are plans. The current plan is wait for forge 1.14+ to get stable, when it is stable then start work on 1.14.
Thats not to say the sponge team is sitting on there asses waiting for forge. They aren’t. Instead currently sponge are modifying the current Sponge code to make it simple to port sponge from 1.12.2 to 1.14, 1.15, etc. This is why you may have seen the latest versions of 1.12.2 loose compatibility with some mods as they were too difficult to maintain.
So while both forge and sponge are hard at work you will need to wait. I have seen many posts wanting 1.14 and some of them wanting sponge vanilla to be ported. Sadly it is a waiting game.
You can gain more in depth information about everything 1.14 on the sponge announcement pages and the latest state of sponge.