Hello,
While I understand the need to build a sustainable business, I completely disagree with removing features that where previously in the free version and making them only available in the paid version.
The product that we have build and are using FusionAuth for has an security required for MFA authentication so when researching what auth solution to use the availability of MFA SMS was an requirement for us. FusionAuth seemed (and still is) the perfect fit for our product with the extensive API and the theming possibility so we can white label our product.
One of the other points that ultimately made us choose FusionAuth was how accessible and community friendly the developers seemed (an forum, github issues to report bugs/features, open roadmap, etc). This action to remove such an important feature from the free version completely goes against that.
Ultimately now we are in the situation that we, in the last 3/4 months, completely build our product based on FusionAuth, but now have to consider switching to a different solution (and rewriting big parts of our product) because an essential feature that we use is being removed from the version that we are using.
Currently buying the paid version isn't an option for us, because just like you, we are trying to build a sustainable business and any additional recurring fees are costs we can't have right now. (Our intend was to switch to the developer version once we have a sustainable business)
The other option, like you mention, to stop updating FusionAuth is quite frankly kind of shocking, to suggest not updating the solution/component that ultimately is responsible for a big part of the security of our product...
If would strongly urge you to reconsider the choice to remove SMS MFA from the free version, make it so that in the free version you can only use the default text templates and only use Twilio, that is completely fine. But do not remove such an important feature from the free version.
Note: the https://fusionauth.io/pricing/ page still says the community edition contains SMS MFA...