I think an online version of this has the potential to be sufficiently different that we can call it "new". Dynamic routing based on real time customer location is pretty fascinating.
Dynamic routing is fascinating, but also potentially frustrating for the rider. Your trip to work could take 10 minutes, or it could take 30 minutes, depending on who else wants to ride at the same time and how "dynamic" your bus routing gets. With a scheduled service, at least you know when the bus will show up. Of course, if it only runs once an hour and not at the time you want, you may still opt for the "flexible" option, but it's not guaranteed to be a win in all cases.
Marshrutkas are just privately operated buses with fixed routes ("marshrut" = "route" in Russian, marshrutka is short for "marshrutnoe taxi" = "fixed route taxi"). They used to be loosely regulated, which resulted in various safety concerns, as the vehicles they drove were barely street legal. They're pretty much phased out right now, and replaced with regular buses.