ZEN, WWK, ROE, M11, SOM
ROE almost stands alone as a set, and SOM was artifact-heavy.
SOM, MBS, NPH, M12, ISD
SOM block had infect and NPH filled out that theme, and then ISD had double cards and a graveyard theme.
ISD, DKA, AVR, M13, RTR
Similar to ZEN block, AVR almost stands alone as a set, and RTR is multicolored heavy.
Wizards did a good job with guild "plants" in the ISD block:
Huntmaster of the Fells will get lots of helpers in the last two sets of the RTR cycle.
Olivia Voldaren is ready for Rakdos deck-making.
Geist of Saint Traft can be in Azorious, helped by Snapcaster Mage and Delver of Secrets .
I will miss all those great artifacts, especially Wurmcoil Engine and Solemn Simulacrum
Let's go guild by guild:
1. Azorious does not need any more help. It already has the "killer combo" in standard of Snapcaster Mage, Geist of Saint Traft, and Delver of Secrets. This combo is even strong in Modern Constructed!!! and Delver of Secrets seems destined for the pantheon of eternally useful cards (Legacy, Modern).
2. Selesnya does get a lot of help in RTR. It inherits the Restoration Angel/Thragtusk combo from AVR/M13. Lets see what Armada Wurm and the other helpers can do.
3. Izzet did not have a single card in the ISD block. Its all about RTR block. Yes, we can include good blue and red cards now, but Izzet is an RTR "thing."
4. Rakdos inherits Olivia Voldaren, and this was a really good card already in SOM+ISD standard.
5. Golgari is like Izzet: no plants in ISD block. It now has a planeswalker in RTR and can inherit the double-sided Green/Black Garruk from ISD, which was a great card in ISD block constructed and next to irrelevant in standard constructed.
For the Gatecrash guilds, only Gruul (green/red) can be played right now in standard and wait for a few helpers. The others don't have a presence. Dimir (blue/black) is underpowered in standard, Orzhov (white/black) has Sorin from DKA, another next-to-irrelevant card in standard, and there is nothing to say about Simic (green/blue) and Boros (white/red) except that they can be played with various strong mono colored cards from ISD block.