As reported in a reddit post and confirmed in a github discussion, Simple Mobile Tools is being sold to ZippoApps which is known for shady business practices.
It is not yet clear whether they will make the app suite closed source (which would infringe the rights of all contributors since they contributed under the GPLv3 license).
In response to that situation, one of the main contributors forked the project under the name FossifyX and will continue to work on it.
There are clever ways to split software via different abstractions that allow to avoid some license features from affecting future developments too. That is to add new closed source features without relicensing the existing codebase.