Maybe two different wallet codebases should be maintained. One for the new version with the new features and other for the standard one based on bitcoin. I fear that the new feature rich client will require an installation program to operate and not be just a simple executable like the old version (and bitcoin). It is the reason I have yet to install the newer version of the CSC wallet and have no plans to do so if it requires an application installation.
Why would you not want to use an installer? I think 99% of the users prefer it as its the way they normally install software. Anyway, we could also just create a zip file that contains the extra Qt files and supply that as secondary install method, then you just unzip and run from the directory where you put it. A second codebase is not going to happen, at least i will not maintain that ...... for now the old wallet still works and i suspect that with the new additions i am currently developing it will all still be backwards compatible with the v1.3 wallet as well as we do not touch the blockchain itself, you will just be missing out on all the new v2.0 release features!