I would think the market for TH would be pretty terrible these days. Almost everyone has some variant of it, more than enough to do the job in abyssea and dynamis. Good luck tho.
It definitely is, but as far as I can tell on Bahamut most of the mercenaries are dual or triple boxing or are in linkshells with people who've been playing together for years. I've only been playing about a year now, and people aren't lining up for an Arisui/Kamome NIN or a BLM who uses HQ staves...THF's utility is kind of all I've got to make the money to finish my STR Shikargar and buy Nomkahpa Mittens.
And as an addendum to the "soloing Namis for gil" thing, it's rough trying to juggle multiple utility jobs while catching up on 10 years of content, and I just don't feel super comfortable soloing Dyna (I'm just starting to get to the point where I will attempt to solo an Aby NM on NIN or BLU without spending 20 minutes reading strats). I'm not bitching about it, but sometimes people who've played for a long time take for granted the knowledge they've amassed from extended gameplay, and it makes it rough for new players when people say "My LS kills Pil in 12 seconds, how do you not have Toci's?" when I'm doing PUG hoping the Corsair knows "SHIELD" means "pop a wing and use WF". Not to say the information isn't available, or that the gear is obtainable, or that something like Dyna is hard; there is just an awful lot to this game, and it's a real challenge to catch up to the elite players.
ETA: I re-read it and I sound like a crybaby. Whatever, I stand by the spirit of it, sorry if the phrasing makes me sound whiny.