There's just under 10,000 guilds that are 10m strict progress ranked and about 20,000 guilds that 10m strict achievement ranked. I am not sure where you are getting the '200' figure from.
Looking over it again, my number is probably pretty off. I forgot that you were still including TOGC in the rankings. Essentially I looked over the top 100 in Europe and US (the other two regions had only a few). The guilds at the bottom of those two rankings hadn't cleared anything in quite a few months. Most were Dec or Jan, kills of Storming the Citadel. Imo if a guild did Storming the Citadel that early but hasn't progressed since then with the 5%, 10%, or 15% buff, they probably are not raiding anymore. There might be exceptions.
Anyway, do you have a count on how many of the guilds in your list are actually still raiding?
It's not just the level of the drops, it's the range. Some stuff doesn't drop in 10 man until later on in the progression cycle (caster shields don't appear until Sindragosa, for example).
I don't know if a 25 man boss early on drops a caster shield or not, but I do know that Anub Heroic drops a 245 shield that is pretty equivalent to the Sindragosa one. Which is what I still use for healing, even though we're 10/12 Heroic
Allowing people to PuG parts of ICC25 and still stay on the list would also "force" all 10-man guilds who wanted to stay "competitive" to do the same. The entire point of the 10 strict ratings is to have a way for people to compete without bothering with 25-mans. Optimally you would just check the gear at the moment of the kill to make sure no 25-man items was used, but until Blizzard makes this possible I don't think there is much you can do.
That makes sense to some degree except for one major thing. Your statement seems to assume people can't currently pug it. As it is right now, 7 people in a guild can clear LK every week in 25 man and you could still fall into 10 man strict.
That's not quite true - if a person leaves the guild and you have not yet been excluded then they no longer count towards your total. The 'stict checker' page sometimes lags by a couple of days - it is purely cosmetic though.
I guess it probably won't be as big a deal for us, we're still at 5, so we can still recruit 2 more without worrying too much. I still think we could remove the restrictions on the first wing though. The current system can be abused at the moment anyway, and allowing 10 strict guilds to recruit from people who have cleared the first wing would still be way less of an advantage than someone that really wanted to game the current system.