We're due a pair of Control expansions in 2020, but that might not be the extent to which we see the game supported in the future. A curious line from Remedy Entertainment's 2019 fiscal report suggests that it might see a wider release on other systems.
Speaking to future sales prospects, Remedy says "Control's high quality, uniqueness and technical innovation provide opportunities to bring the game to new platforms." It's already on PC, PS4, and Xbox One. Given its shaky launch on consoles, it seems as though some technical wizardry would be in order for a Switch port to be feasible. (Although, Saber Interactive managed it for The Witcher 3 on Switch, so nothing is outside the realm of possibility.) A more realistic reading might indicate that Remedy plans to re-release Control on PS5 and Xbox Series X at some point.
As for Control's commercial performance, it seems to have done okay but not great. Without mentioning numbers, Remedy mentions that "post-launch sales have settled on a good level" while also admitting that a light marketing budget probably hamstrung launch numbers. Remedy's cash flow for the year was slightly negative -- about $430,000 or so -- but that appears to be largely because the first wave of Control's revenue was contractually dedicated to paying back publisher 505 Games' marketing budgets, and then the timing of royalty payments works out in a way where they'll mostly trigger in 2020.
Remedy's plans stretch far beyond Control, though. Remedy has a goal of "launching at least one game or game expansion annually." Right now, there are four projects in the pipeline: the aforementioned Control expansions; the singleplayer component to popular first-person shooter CrossfireX, which is supposed to arrive on Xbox later this year; a third game that's unannounced as of right now; and a project that's codenamed "Remedy Vanguard," which is some sort of ongoing multiplayer game, possibly within the games-as-a-service sphere.
Those latter two are a long ways off -- which is probably evident given that they're still unannounced and codenamed. They're both entering pre-production soon, as small teams have been prototyping. The third game has a dedicated staff of 20 people, and Vanguard has a team of 15 people, but those will surely increase soon as Remedy ramps up development.
Financial Statements Release 1.1. – 31.12.2019 [Remedy Entertainment]