People come and go
As a project maintainer, you learn that people truly come and go all the time.
Without knowing where from or how they found you and your project, you can find an awesome and well-written improvement provided to the project on a rainy Tuesday morning from a name you have never seen before. Other times, you will find the project completely deserted and that you are the only one to have done any changes to it for an extended period of time.
The contributors who flocked to the project just a while ago and who helped with so much stuff, added good code and helped answer questions from new users just suddenly vanish.
The low barrier to entry is also a low barrier to exit. People get bored, they change jobs, they find spouses, they get kids, they switch to a competing project – in a sense, every other Open Source project in existence is a competitor as in they also want the time and energy from contributors and every contributor only have their limited amount of time and energy to spend on Open Source. If you are unlucky, they spend their precious time in another project.
Sometimes people will leave your project in the most inconvenient moment. We can only pick up the pieces and move on.
Roadmaps and planning in a small project should probably focus on what the project wants done but without dates and tying the items to specific releases far into the future.
Communicate the direction and vision and work towards getting there, but without assuming that certain people will be there over a certain period of time. Hope and wish that they still will be around, and appreciate them extra much when they are.
If you are lucky, you will have enough maintainers and regulars to drive new features, work on bugs and ship new releases.