I feels that open sourcing the projects harms my own ability to continue work on it.
Future versions planned to be paid for example (current one will stay free of course), an i expect that this will allow me to make this work fulltime and self fund future developments. Basically i am even now in process of raising outside investments for this plan.
Having side by side a copycats with removed payment options will obviously harm the business.
Please note that I don't want to discuss this topic.
There is plenty open sourced tabs managers to experiment with.
For example i can recommend a very close analog to Tabs Outliner - Sidewise Tree Style Tabs. It's sources is available. Or Sesion Buddy - they also recently published a version with an opened sources.
On your local PC, without distributing anything that is derived from my sources or include them, you also can do anything your want, as this is all a JS and HTML, it's not that hard actually to make changes, even despite the fact that JS is actually generated and processed by compiler, it's still not much harder to make simple changes then if they will be present in original form.
Future versions planned to include ability to integrate externals addons, distributed by other authors, which will be able freely manipulated the tree DOM, but when this will happen - meantime i don't know this, so maybe it's not worth to wait. And also unlikely you will be able to make so drastic changes as you describe.
Need to say that after reading a list of changes that you propose i am actually recommend you to write a completely new extension, from scratch. Looks like that the logic of it's operations is very different from Tabs Outliner.