I'm not going to claim that FFXIV is dying or anything. Though that is probably inevitable, as with any MMO (even WoW will die off eventually). I will say my FC is going through the same thing as the OP's. In addition to that the 8+ linkshells that we use to pull back-up people from for our Coil groups are also empty. The fishing linkshell I'm in, and crafting one, have both pretty much died. It's not uncommon to be the only person on. We spent over an hour the other day looking for one dps/tank/healer (because we have people with multiple classes leveled) so we could do Turns 1-4 of Coil. Our group doesn't have a bad attitude, or a bad name for ourselves (we can clear the four turns in under an hour). Most that have pugged with us eventually actually join our FC. There just didn't seem to be anyone on who hadn't already done Coil, or wasn't already in a group (there were 2 other groups in Party Finder for Coil, each missing 1-2 people). Mor'Dhona has also seemed a lot emptier. The huge dense crowding is gone, and there's a smaller sparse crowd there.

All that being said, I don't play on Mondays. We raid Tuesday and Thursday at 8pm CST. I don't even sign on Monday. For all I know there could be a server queue then, and Mor'Dhona/Wineport could be overflowing. Playing one day a week to knock out content in a few hours doesn't really fit my idea of active.. but maybe that's also just my server, and others haven't shown a decline at all. I don't know.

FFXIV isn't on the brink of going F2P or shutting down or anything though. I do believe they have got/are getting, a good influx of people from the Steam launch, and from the PS4 launch. Yoshi also never was out to maintain over a million active subs. If I remember right his goal was around 600k.