Honestly if your guild is still around but not recruiting new members or playing new games, CF is going to be harsh to do without allies. I'm 36, married, work 60 hour weeks, have 74 employees, a 2 year old (the similarities between the 2 are astounding sometimes) and not enough time for gaming - if I get one night a week that's good. That being said, I spend time on the oversight and management of the guild and try to make sure we're playing games together and recruiting new members as we go (more of that than actual gaming, fallout 4 notwithstanding).
We have around 30 active players in about 6 games and another 20-30 who will show up for a bit and disappear after a couple months when a big release hits. At primetime if we have 12-15 people on at once in the same game, that's a decent showing. Sometimes we'll have 20+, but that's right as the game releases and everyone has time off. We've picked up players from SB as we've moved from game to game and bumped into them, and picked up a few quality players in every game we played long enough to recruit in (WoW, SWTOR, AA, etc). We've kept the forums and website updated, we moved comms from vent to mumble to gamevox, and everyone still logs in to comms just to hand out and talk and play games together when they have time - even if there isn't a "focus" game to play at the moment. At any time you can probably find guys playing SMITE, Rocket League, D3, SWTOR, AA or just sitting in channel talking while they work from home or use the interwebz. I can't remember a day in the last year when we didn't have at least 8 people in mumble (or gamevox now) even if they were just in the AFK channel.
We have a facebook group, voxer chat, slack and a facebook page and we've done local meetups, a guild cruise (10 gamers on a cruise ship, drunk, is entertaining), had a wine tour and 3 weddings in the last 5 years.
We're small, but we're not stagnant. Keeping a small guild running takes time and effort, because every member you lose to RL hurts much more than a guild with 100 players who loses 1 and replaces it with 3, because that member had a job and a purpose that effects everyone else still playing that much more, and it starts the domino effect of everyone dropping off.
The massive zerg guilds who play multiple games and have 100+ members that follow them around from game to game as they get released are going to be an issue. Yes they mass quit and disappear to another game as soon as it releases, but for the first few months of a game they bring pain to smaller guilds. XoO, Warrior Poets, Oran'Thul, and ForestCrow all do this and of their 100 members, maybe 10-15 are actual quality players with a clue. The rest are sheep feeding the engine of those top tier players in the guild, following the herd hoping for some recognition of their "efforts" for the "team". They don't care if their members are unpleasant people that everyone hates in comms, they don't care if they recruit spies, they don't care if they spam invite players at the starting zone - as long as they show up to fight it's all good.
They'll even truce with each other and double or triple the zerg rush to win if it gets them more members and more youtube viewers because the leaders directly benefit from a massive sheeple base by the structure of the guild.
I think honestly the SB guilds will have to suck it up and form some uneasy alliances to survive the first few campaigns (till the zergs move on). it should be interesting to watch. Game mechanics will be the final deciding factor of just how big a guild or alliance needs to be to make it.