I am personally invested quite heavily in TNET at the moment as I have learnt how it works and have heavily customized it to my particular needs.
The fact that it is open source and well commented and well structured enables me to learn it and do whatever I want and is invaluable.
However, just as NGUI was the absolute best GUI for unity and still is, imho, uGui essentially replaced it and by pulling numbers out of my @$$, probably hurt the sales of NGUI.
Although, I have heard rumours that Aren was paid for the efforts.
The same thing is probably happening with Unity MultiPlayer, and thus Arens choice to turn it into an editor extension for serialization purposes, (just a guess)
I would personally prefer to see the underlying code base become an extension to Unity MultiPlayer, being a build out of the features for ease of use, rather then shifting to a serialization system. I think that the purpose of having the owner of a unity asset on the asset store is specifically for this! I would love for Aren to make TNET able to utilize the new Unity Multi Player system under the hood, so to speak whilst at the same time maintaining the same high level function calls.