He'll be gone on the 20th of January, and that's that. There are no moves he can make that ends with him staying in office, and any additional attempts he makes will fail either before they begin, or shortly thereafter.
Speculation about civil war, the military running another election, etc. reflects a fundamental misunderstanding of Republicans, Trump, and their motives. Trump is making fistfuls of cash off his morons right now, shifting efforts to a special counsel removes those funds from his control. Deploying the military or declaring martial law would result in the global economy nosediving into the worst economic depression ever - not something that Republicans will allow to happen. First and foremost the Republicans stand for profit, and nobody profits from any of that.
Everything he is doing now is an orchestrated series of dramatic acts intended to manipulate his morons into supporting him during the post-Presidency. It is literally all show. Don't worry about it.