Here's my thoughts on CV as support, and increasing the number of viable strategies.

TL;DR Think for yourself and don't get stuck doing the same thing over and over, It should be and it is up to the playerbase to decide what strategies are viable. Some would say it's already been decided. I'd say it's constantly changing. For some years now I'm sure you've noticed how every season the 'meta' settles down and everybody gets complacent with it, IE starting ward trinket on all 10 players at level 1. That's all well and good, I fully understand the place of any meta that settles down and it's all subject to change. What I'd like to elucidate for you is the usefulness of clarvoyance, and also vision itself as a resource specifically as a support. You've got to sacrifice something to take CV, so lets say you sacrifice flash-which was what was taken in season 1 when clarvoyance, and passive supports were more league of legends speed. I'd like to talk for a moment about the pace of the game. Every game is different, but if you've noticed the meta as it is influences the pace of the game and makes everybody feel safe and contented. One other thing I'd like to mention before moving on is the goal of the early game, rune'ing for it, dorans item starts, flash ignite etc are all greedy in that you're investing heavily in straight winning lane early on and the game becomes less about 'strategy' in my opinion. Both teams do this, and they make a sort of agreement to do so. Hence the meta. I'd say that these agreements are also a limitation on the players themselves, of course they are willing to be limited in this way if it's considered the 'viable and safe' way to play. So the number of viable strategies is limited eh? Tell me something I don't know. Let's a second step out of all these traps of getting caught in a pattern and doing the same old stuff. So we all know that information is key, which is what vision is. Vision itself is not often seen as a resource on par with gold experience etc. I'm proposing you look at it in this way. Seeing this you can make up your mind if clairvoyance is viable, that's a part of it. After Sightstone gets bought usually, unless the support player forgets they will trade their ward trinket out for a red trinket. I'm going to make up a little meta real quick, let's say: If there is no stealth/little stealth on the enemy team, you'd be better suited as a support considering your role is not only vision control but getting this information in the first place. The vision you've gotten is also a part of vision control and I'm sure if you've ever been heavily counter warded you know you'd have less control. I'd just like to put that out there also, that I think the blue trinket suits the support role quite well and arguably suits the role more than red trinket does in many situations, if not most. It's under used, and I think the league player base condensing what's 'viable' and under-utilizing potential strategies. I think it's up to the players as to the kind of game they want to play. I think we've seen enough so far that relying on Riot's balance team to increase the number of viable strategies, I'd also like to mention that when increasing the number of viable strategies also increases depth of mastery, which is what Riot has stated is what they've perceived is why we play this darn game in spite of it falling short some times. I think the player base has to save itself, and not rely on mommy Riot games Balance team to balance based upon the meta, etc. They don't want to force us to do anything, hopefully and we don't want to be forced. Possibly my concerns here are not commonplace and I'm the minority, in that case I accept that. If i changed one persons outlook then I consider I've succeeded.

TL;DR Think for yourself and don't get stuck doing the same thing over and over, It should be and it is up to the playerbase to decide what strategies are viable. Some would say it's already been decided. I'd say it's constantly changing.