The "going for herd immunity"-strategy is limited by the health system, one limiting factor is the number of intensive care units. You don't want the number of people needing intensive care to be higher than the available units. If you consider this, for example for germany there is a modelling that shows that R0 = 1.25 is still too high (in german: https://www.dgepi.de/assets/Stellungnahmen/Stellungnahme2020Corona_DGEpi-21032020-v2.pdf), and it would still take at least one year until heard immunity.
That means all over 2020 there must be some kind of restrictions, hopefully not that strict as we have them now in many countries, and I fear that free travel between countries is the last thing we will get back.
Everyone is hoping for the vaccination!