None of those options would work.
There just needs to be more 'ramp up' in the difficulty of a raid, at least on normal mode. For 10 and 25 man. First few bosses should be very simple, and give a smattering of loot that should help people gear up for the next few bosses who are a bit more challenging. Finally the last few bosses should be very challenging, almost on par with early heroic modes.
Thing is, they sort of did this already with previous tiers. Dragon Soul did this to a degree (ignore the quality of the content, just the difficulty), Morchok was a complete joke, Yor'sahj was simple when you learned the mechanics and Zon'ozz only required simple raid cordination. Then Hagara required more coordination and knowledge of the tactics, with Ultraxion being a DPS and healing check that pushed people to play better. Blackhorn was even more challenging, requiring good burst dps, raid awareness, cooldown usage and priorities on killing certain adds. Then Spine was an utter hellhole for many non-hardcore guilds that they struggled with for ages, with Madness being the only issue with my example as it was slightly easier then Spine (though still more difficult then half the rest of the raid). The heroic modes then ramped up almost in the same order, with Zon'ozz being the sore thumb due to the sheer amount of healing required.
If they just keep doing that, people will do fine in normal modes. The problem with ToT was Horridon being a brick wall right after Jin'rokh, and the rest of the dungeon being relatively simple in comparison up until Dark Animus.