I think this edition has gotten enough patches already, but with a faulty core system, problems are bound to arise sooner rather than later.
Fixing the Dark Reapers or the Ynnari will solve nothing, just shift the unbalance.
I think GW will have to rethink their codex system, you simply can't just bolt-on rules on top of rules until they make no sense.
A suggestion would be to keep all points cost for all armies in a separate book, have the rules in one book, then have codexes with special scenarios with special characters, for a lot of fluff flavor.
Most special characters should then have a base generic character to build on, so the models could still be used, for example Eldrad could be used as a farseer.
Players can then of course make up their own special scenarios where special characters can be included, they are simply just not suited for competitive tournament play. Forge the narrative, imagination is the limit, or whatever.
This would force the fluff writers to write good enough fluff to get the codexes sold, it would be easy to update points, rather than calling it a new edition, by releasing a new point cost book. Even simpler if it's done digital, which goes on to a digital armybuilder application.
A lot of players in my local gaming club grows bored fast on the standard missions, so they'll still run and buy every new codex ASAP, simply for the new scenarios.
Sorry for the long rant.