I understand your concern, and I also remember the heavy feeling of getting ready to jump ship.
These two main points will help.
1: If you stay with Maya, there will come a point in time where your blender add-on support concern will actually be THE concern for Maya itself.
There will come a time where that company will no longer support or even allow you to download or install the older versions and you will have no choice but to use the newer version that they will supply and approve of your usage on, and eventually there will be a de-sync with Maya and the developer of any mythical add-on you are obsessed with whom developer may choose not to continue working on.
When that happens, your current fear of what will happen if you use Blender will become a reality in Maya.
But what if you use Blender ?
Every, and I mean EVERY version of Blender right down to version 1 of Blender is available for download for FREE, you will never have to jump through license hoops to get it.
And since you will ALWAYS have access to whatever is the older version of Blender to get any equally old add-ons to run, you will…in essence, have an eco-system where an add-on never truly dies.
Imagine…an eco-system where add-ons never truly dies…Welcome to Blender.
2: After the old version of Blender has executed the old add-on that does its job, you can always open that blender file in the NEW version of Blender to continue.
The open-source nature of the add-on IS its strength, someday you might choose to learn Python and update it yourself if it matters that much to you, but again, it DOESN’T MATTER
Because you can always download the older release of Blender to run it…
The very fear that you are having now…is actually a very real fear with your CURRENT workflow in time instead…
In essence, you are actually concern about the very software that you are using, and accidentally projected that fear onto Blender.
Welcome new Blender user, into the land of Freedom
And let’s face it, Blender is now good, like really REALLY good, so much so that it is really on the artist now