This graphic is is an incorrect view.
You are mistaking an implementation with a hard fork proposal
XT, BU, and Classic are proposals for a hard fork, not competing clients. A hard fork is a call to change the global rules of the network. You can't have 3 competing sets of consensus rules, because this will eventually create 3 separated blockchains that are inoperable with each other.
In this case, if you have Core, Classic, XT, and BU, running together: XT, Classic and BU can accept Core blocks, but Core cannot accept Classic or XT blocks over 1mb, Classic won't accept anything over 2mb from XT or BU nodes, and XT won't accept blocks over 8mb from BU nodes. BU will accept all sizes. Eventually you will get a 1mb chain, a 2mb chain, and an 8mb chain with enough time, with BU not caring because it has a higher default cap than all of them. Technically at least 2 of these are altcoins depending on which one you want to call "Bitcoin".
Now, such a scenario is highly unlikely, and for that matter average block size is averaging 50% of 1mb right now so this would not occur at first, I am just trying to point out that the fallacy of what this graphic is showing. With enough time 4 distinct blockchains would appear.
The majority of the network has to agree to the same set of rules. This graphic is suggesting we fork Bitcoin into 3 distinct chains. That isn't how hard forks work.
An implementation would be like BTCD, which is a version of Bitcoin Core written in the Go language, or Bitpay's Bitcore which is another version. The implementations are based on the current accepted consensus rules, in other words are based on the winning reference code. If Classic manages to pull off its hard fork, then BTCD and Bitcore will have to be updated to work with those rules. To this I agree, the more implementations the better. But, those implementations still have to follow the generally accepted rules as to what blocks are acceptable or not, or their blocks will be rejected.
So please stop passing this GIF around, it is mis-information.