The answer is no for so many reasons. Basically I wouldn't put any money towards a Trek Marlin except the absolute basic needs to keep it safe till I figure out my next bike. The bike is a very basic bike designed to look more like a mountain bike but perform more like a heavier cheapie hybrid. MT200s some of the best cheap brakes out there and work well and rarely have a lot of issues however a crash can change anything at any point and is not a reason to get rid of a system because of it (except replacing the damaged parts with like parts).

Most of the mechanical disc calipers are going to be more expensive than the MT200s or are going to suck using tiny pads and poor actuation. They simply aren't worth it. I would just put new hoses on the MT200s or get a new set and be done with it and start saving towards a mountain bike or whatever bike you are looking for.