You would have to increase the number of buses and their frequency on the routes. The consequence of this is that there will be fewer cars (and maybe bikes) on the roads, which mean that buses can go faster, which means you don't need to add quite so many.
Probably the net result would be to increase the number of buses, decrease the overall traffic, and increase everyone's mobility. It may increase the number of tourists (could be good or bad), and will probably cost everyone a little more than expected.
"will probably cost everyone a little more than expected."
A little less on a large enough system wide scale. Hard to find a cheaper way to move people around, quickly, on land, in any weather, than a properly applied bus.
Tourists in taxis is definitely not cheaper and rentals are even worse.
I admit trains/subways are cheaper if the utilization level is high enough, but it has to be Really high. If "your" subway stop has 50,000 potential riders that'll work. But where I live a subway stop by my house would have about 50 potential riders, which is a bit of a financial problem.
That might happen. However, changes to systems which require "let us change a lot of things, and afterwards, things might even be better!" tend to go nowhere.
I'd love for people to work on making bus riding more convenient for people right now. The fares aren't really the problem. It's the bus going where I need it go in a comfortable fashion.
Probably the net result would be to increase the number of buses, decrease the overall traffic, and increase everyone's mobility. It may increase the number of tourists (could be good or bad), and will probably cost everyone a little more than expected.