indeed, clearly the Top 14 has become for many reasons stated in the past a home-oriented league. And yes, you mention the depth of teams, clubs now not only need one hell of a XV but they also need guys off the bench who can offer just about the same punch and have a huge effect on the game.
Toulon won arguably because of their depth, not necessarily the Top 14 final against Castres specifically, but their whole season, on both competitions/fronts. They even said it themselves, can't remember who, probably Laporte: "last year we fell short in the Top 14 despite making the final because we fell victim to just way too long a season competing hard for both ***les. This year, we rotate our guys much better and have installed the depth we need to make sure we keep fresh and competitive the way we should".
Again, other clubs will look to follow in those footsteps. Racing are probably the classic example, more so than Toulon in fact, of the team that just doesn't even care about playing time and coherence - they'll just buy a shiit-ton of guys at each position just to 'make sure'.
A full season (counting both fronts) for Top 14 clubs is just literally IMPOSSIBLE now with just a good xv and some okay reserves, you need big names throughout the roster. You look at clubs like Montypellier, Paris or Castres who are top drawer acts just can't play on both fronts with consistency. It's just too much.
Toulon have a culture of utter excellence, obviously helped a whole lot by the big bucks, not just to write big names on the roster sheet, but also other stuff like the medics, the cryo-therapy stuff, etc...etc...how many teams can hang with that ? - this isn't Hollywood.
Surely the H Cup is just a step too much, an excess dimension to Top 14 teams. English clubs (bar Saracens with the huge exception) just aren't good enough to progress far in that competition, Irish clubs are fresh as hell and very good anyways - our clubs come into this thing like a big thorn in their spine and just cannot seriously intend to compete in both French AND European championships in a single year.
Ideally, the H Cup would be played every 2 years or something, with all local competition coming to a halt to make way for it.
I don't mean to cowardly put it all on fatigue and calendar, but Toulouse and Clermont both got SMASHED in the H Cup, and they both failed quite miserably AT HOME in the Top 14 campaign. By the time they get humiliated on the European scene, they get back on time to the local competition to get ousted at home. By aiming at two targets, you hit neither the one, nor the other. Too much happening at the same time, and at the highest level. I really think this plays a role for our clubs. The Top 14 is just too much, far too weighty, and leaves absolutely no room for test match Rugby first of all, but the H Cup seems quite excessive itself.