What are your goals?
- To fix many of the still open bug reports.
- Investigate any security issues in the code.
- Performance improvements.
- Lastly would be to add new features.
phpBB-EOL is a project that aims to continue work on the phpBB2 code base in order to improve it and keep it alive.
I don't see phpBB2 as a finished product. I still see flaws in the code that were reported many years ago that still remain unpatched.
Even though support for PHP4 will soon be over I don't feel this affects the project. PHP5 will be in use for a while. PHP4 was released in 2000 and can still be found installed on servers 8 years later. PHP5 will remain in use even after the release of PHP6. With this being the case phpBB2 is still of use to many.