Without a technical model of how, or any examples of why we would do this/defined case circumstances to abstract pros and cons, it would be very difficult to even have a metric to determine how it is 'better' or not let alone unique from color coin models...
It is of the utmost unlikelihood to happen with Bitcoin, as it would require a seriously hard fork, and no incentive to merge with smaller projects. (Of course subject to change, but surely not something to plan on.) Several small projects may band together to implement that kind of technology but again without any technical detail, it's very hard to assume how or why and thus determine any benefit.
Even if you launch a new coin, or multiple coins as per your desire that do share a blockchain: How would it be technically implemented, and how is it any different than colored coins, or any typical asset marking method currently being utilized similarly? On this chain, What Is the difference between COINB and COINC? Whats the difference between if COINC is independent, or a colored COINB coin, if they are on the same blockchain?
Why are we trying to answer a question, without a defined reason to ask it? (Not that I don't believe in this practice for inventiveness, but rather let us find a reason why we would do this, and what benefits could be accomplished by doing so.)
So, to answer your question with a question, What benefits could we accomplish with this not already done so with current models? What is the difference between that result and how current designs would implement that solution?
As far as implementation of the general concepts, only without a shared blockchain, single features of this design are already achieved independently:
https://en.bitcoin.it/wiki/Merged_mining_specification facilitates the mining of multiple chains together.
As far as utilizing and managing multiple coins through one wallet, There are multiple wallet projects such as
http://coinomi.com/ and
http://ufasoft.com/coin/ that allow multiple cryptocurrencies to be managed through one client. (Not sure if ufasoft is still maintained)
To answer your questions i do not have a full grasp of colored coins, but the difference i see is that colored coins are a "marked" output, but it is essentially one emission.
Your question on technical implementation, is a bit ahead likely, i would introduce a new kind of output that while processed the same as normal, it may have special rules, such as indivisibility or some such.
I need a defined reason to ask a question?. I was not aware.
Benefits of such an implementation include almost all the benefits that brought about talk of side chains and colored coins in the first place.
The purpose of this question is about doing it all on one chain, using one wallet,or a wallet that filters unwanted emissions. I think it becomes less cumbersome for the end user, instead of merged mining and multi-wallets.
