I could imagine that cities of the future will have free high-speed internet and public transportation, with tax money pooled to enable movement of people and information with smaller friction than in a system where each individual has to provide for themselves.
In Tallinn the free public transportation did increase the mobility of people in lower incomes. However, it's perhaps also worth mentioning that the growth in the use of public transportation was not only by the expense of driving, but it also reduced walking and cycling.
Based on the experience in Tallinn it might be good to combine it with free public bicycle renting system.
I've visited Tallinn many times, warmly recommend others to do so as well.