Which architecture to choose
There's a tendency to think that a more evolved architecture, like the microservices architecture, is better, but that's an oversimplification. Each one has its own set of strengths and weaknesses.
The first one is the fact that almost every small application will start as a monolithic application. This is because it is the most natural way to start a system. Everything is at hand, the number of modules is reduced, and it's an easy starting point.
Microservices, on the other hand, require the creation of a plan to divide the functionality carefully into different modules. This task may be complicated, as some designs may prove inadequate later on.
Keep in mind that no design can be totally future-proof. Any perfectly valid architectural decision may prove incorrect a year or two later when changes in the system require adjustments. While it is a good question to think about the future, trying to cover every possibility...