Deck13 has been answering some fan questions via its official Twitter account, revealing some new information about The Surge 2. According to the developers, the game will feature new game plus, it will have double the number of weapon classes (than its predecessor) and the weapon skill system will be enhanced and upgraded.
The team has also immensely upgraded the drone and what you can do with it in terms of ranged combat (the drone is now physically mounted to the exosuit), there will be more bosses (at least twice as many boss fights. Some will be smaller, others even larger than the bosses in Surge 1) and a large variety of enemies, the AI will be improved/enhanced, and some enemies will have guns.
The combo mechanics have been completely rewritten, lots of fighting and combo mechanics have been upgraded and there is a lot more flexibility in cooldowns now. Furthermore, levels will be more interconnected and traversing the world is possible in many more layers now.
Last but not least, The Surge 2 will feature several online features, however, it will not support a co-op mode, at least when it releases in 2019.