is GP10 still a viable choice as support?

You list primarily tanky supports, who were hit the hardest with the removal of Heart of Gold. This leaves two other GP/10 items: Philosopher's Stone and Kage's Lucky Pick. I ignored Avarice Blade as I don't feel it compliments the support role.

A Philo stone can build into Shurelya's Reverie, Eleisa's Miracle, or Ohmwrecker. Shurelya's is still a great support item, and Eleisa's reduces the cooldowns of the summoner spells Heal, Clarity, and Clairvoyance. It can also free an inventory spot if purchased early enough! Ohmwrecker is outshined by both items, and I don't recommend buying it on a support.

Kage's Lucky Pick turns into Shard of True Ice, Twin Shadows, Morellonomicon, or Will of the Ancients. The first two are most viable on a support, and the Shard continues to provide GP/10.

So a lot of things affect whether GP/10 is still viable.

For a Philo Stone:

• Did you take Heal or Clairvoyance?
• Do you need extra sustain?
• Does your team need a Shurelya's? Is anyone else buying one?

For Kage's Lucky Pick:

• Does your champion benefit from extra AP?
• Do you need additional CC?

Another new item is the Sightstone. For an investment of 950 gold, you can place up to 2 wards at a time, with each ward lasting 3 minutes. The Sightstone holds 4 wards total and refills when you return to base. This breaks down to 50 gold/minute, and starts saving money after 19 minutes (assuming you immediately place wards when available). It also provides +180 health, making it a strong choice for tanky supports.

Previously, GP/10 items were essential to compensate for the cost of wards. This is largely mitigated with the usage of a Sightstone, freeing money for other items.

A Philosopher's Stone costs 700 gold and pays for itself in 23.33 minutes. Kage's Lucky Pick costs 765 and pays for itself in 25.5 minutes. These times are halved if you sell the item. Because it takes so long to make money from GP/10 items, it's best to buy them as early as possible.

Compare this to the gold granted from kills/assists. A champion who hasn't been killed is worth 300 gold, and 50% of that for an assist. The more times a champion is killed, the less money the kill rewards, with a minimum of 15 gold.

Since 2 GP/10 items provide 60 gold/minute, you have to get a 150 gold assist every 2.5 minutes for assists to equal GP/10 items. You can get an additional 5 GP/10 from Quints and masteries, resulting in 90 gold/minute and needing an assist every 1.66 minutes.

The new pick-pocket mastery offers an additional avenue to generate gold. Unfortunately, this isn't very viable on melee supports.

While supports are no longer required to get GP/10 items to support expensive ward-buying habits, these GP/10 items are still cost-efficient for longer games AND they upgrade into items that are very useful for most supports.

Ultimately, the decision to buy GP/10 items comes down to play-style and preferences. If you prefer to play aggressively and need extra stats to stay alive, skip GP items. If you're trying to maximize gold gained, GP/10 is still the better choice (unless you can get an assist every 1.6 minutes!).

tl;dr: GP/10 is still very viable, especially since those items build into new support-focused items. However, it's no longer a necessity since the Sightstone makes warding much cheaper.

Yes, it is still a great help to any support. Philo still builds into useful things, it's nerfed in stats but the GP10 is the same. On the other hand Kage's lucky pick got nerfed in GP10 but now it builds into shard of true ice which keeps the GP10 at the end of it's build and has a useful slow active. It is still viable to buy GP10 perhaps even more so now because there are more support items.

On the other hand going no GP10 and all assists is actually more viable because of the new sight stones. However to go without GP10 is very risky. By building with a larger focus on kills and assists and less on a safe gold setup, you essentially force yourself to either get kills and assists or significantly reduce the effectiveness of your ward control if you fail. The sight stone is not capable of warding the entire map. Only your lane, so you still need to buy wards and you need to buy oracles/pink wards as well.

Put more simply: It's snowball or bust without GP10

I think support as a whole will gravitate towards winning the lane as opposed to wait until the gold items kick in.

Sightstone is by far the best gold item right now (saves you up to 350 gold every time you shop), and you can't buy it at the start, so you have room to explore there. I like to start 0/13/17 cloth+ward(s)+pots, and go crazy aggressive with my trading advantage. By level 3, I can zone pretty much anyone.

I feel Philo stone is simply not worth it anymore with the health regen nerf and Flask, and Kage's also doesn't give you the stats you need on tanky all-in supports. The loss in gold is mitigated by Pickpocket, the ambient gold increase, and gold quints. And assists, of course.

Philo stone and Kage are more snowbally items at this point, I think. Get them when you have the advantage, but don't sacrifice your usefulness for them.