Not only the proton, the soyuz will have also a version without the 3º stage

[kunok]

The new name for this version will be Soyuz 2LK. It wouldn't use the third stage, the Block I, using directly a Fregat upper stage, it will look a lot like the old vostok.

Is made to be able to get 2 to 3,9 ton to heliosincronous orbit, filling an actual gap between the standard soyuz and the soyuz version without the lateral boosters.

This is my source (sorry in Spanish, my googlefu don't encounter anything in english, but look the pictures) http://danielmarin.naukas.com/2016/11/30/soyuz-2lk-el-nuevo-cohete-ruso/

Original sources in russian:

• http://www.vz.ru/news/2016/11/21/844867.html
• http://izvestia.ru/news/640024
• http://samspace.ru/news/press_relizy/8680/

[kerbiloid]

Modders have some time till 2020 when it's scheduled.

[kunok]

1 hour ago, kerbiloid said:

Modders have some time till 2020 when it's scheduled.

In real world they need to make modifications to make this modular change compatible, in KSP we just quit the subassembly, so already done