There is not going to be a sudden relaxation of all the requirements when traveling into Thailand, regardless of the departure country. As is beginning to happen, there will be a partial relaxation of the requirements when coming from low risk countries. This could evolve into bilateral agreements allowing quarantine free travel from certain departure points.
For travel from high risk countries, it is unclear how things will evolve. Much will depend on the effectiveness of vaccines. If vaccines are developed that reduce the risk of contracting Covid-19 by 70% and the risk of being