It sounds like there won't be any more updates to MAMP Pro 5. MAMP Pro 6 will be released in 2020, possibly January.
See below from developers.
We will be releasing MAMP PRO 6 in 2020. MAMP PRO 5 will not have many more new features added at this point.
MAMP PRO 6 will have, at first release
Redesigned interface with less stuff/buttons
MySQL 5.7 (Additionally MySQL 8 will be added, but not in 6.0)
Easier Remote feature, more functionality
Other features as well …
We should have a beta in early 2020, maybe January. If you would like to check out a beta, I would open up a ticket late this year, and we can send you one when it is ready.