Joomla as I understand are no longer doing the normal process like so:
- 2.5 (Long Term)
- 3.0 (Short Term)
- 3.5 (Long Term)
- 4.0 (Short Term)
- 4.5 (Long Term)
Instead they will me using the Semantic Versioning process.
The Joomla Roadmap shows you the upcoming versions:
So from now on, it will be as follows:
- Major updates (e.g 4.0) - Big API changes. A migration process will be required.
- Minor updates (e.g 3.5, 3.6) - 1 click update
- Patch updates (e.g 3.5.1, 3.5.2) - 1 click update
So basically every Joomla 3.x version will be a 1-click update, however, I would still suggest looking through the changelog provided for each minor release, just to be on the safe side.