As the title states, I would like to suggest an offline mode, one with an intact progression system. There's a lot of reasons for this suggestion that I think many people will agree with.
First off, some people don't have consistent enough internet for playing online, but they might still love many of the ideas or gameplay features of Marauders. Getting those offline players to purchase the game is just good business.
Second, there's a skill gap issue for some players. Not all players are ready for online combat, and are going to be turned off by the PvP aspect of the game. An offline mode could work as a training ground for players who want to play online, but don't believe that they are ready for it.
Third, there are many bugs currently in the multiplayer that seem to occur specifically with other players in your crew. At the same time, going into a raid without a full crew is extremely risky, putting players into a no-win situation. Setting up an offline mode would give developers time to fix those issues while players unsatisfied with those bugs can scratch the itch in their own isolated version of the game.
So, with those reasons in mind, how would I suggest its implementation?
Simple. There's no need to bother making a big campaign out of an offline mode -- the gameplay and atmosphere are compelling enough on their own to incentivize play. Just drop players into maps without other online players.
The only gameplay issue I see this causing comes with the contracts that require Marauder kills, but the solution to this is honestly pretty simple to me as well -- just make a few AI in the raid act as Marauders. Functionally, they'll be the same as the other bots on the map, but perhaps with randomized gear and funny names generated on their keycards. Their only purpose is to let players continue progressing through the game, so they simply need to exist in some capacity. Beyond that, they can be like every other bot.
Please consider this idea. Thank you.