For me it would be activating the stabiliser... ideally there'd be no stabiliser, sensor shift stabiliser, electronic stabiliser, sensor shift + electronic stabiliser (fast movements are countered by the sensor shift system, including rotation, and the electronic stabiliser balances out slow movements, and is able to recover the sensor shift system from awkward positions). All versions without electronic stabiliser can be with or without crop.
Then bump up the bitrate and offer different quality settings. i.e. Standard which is as it is now, and then quality dependent settings that have a raised limit of say 50-80 Mbps, but otherwise represent say q18, q20, q22 and q24 in x264. So even q24 can bump up to 80 Mbps if really needed. Makes the actual size less predictable, but it would be small where possible, but big where needed.
At that point I personally would be happy already and would consider it.
Clean HDMI out doesn't sound like a huge issue for them to fix, though who knows. Articulated screen is nothing that can be fixed in firmware, obviously, and I kind of doubt we will see this on a rugged camera from Pentax. I think only Panasonic makes cameras that are rugged and have an articulated screen. An external screen for that seems to make more sense. It's bigger, can offer some stuff like focus peaking, might even be able to act as a recorder, the resolution is higher and you're more flexible in positioning it.
dpreview did an interview with Nikon at QP+, and Nikon said that they recognise that professional photographers these days need to do stills and video. Obviously they don't want to give up the professional market, so they will have to focus on that. They also said they have a dedicated video team at Nikon.
CP+ 2014: Nikon Interview - 'our cameras need to evolve': Digital Photography Review
So... Nikon is pushing video. The D5300 has some amazing video quality, including higher bitrates (though not very high, but hey... it's something). Obviously a entirely consumer focused DSLR will not be giving you the controls you'd want as a videographer, but I'm fairly certain that the D7200 will be offering the quality of the D5300, but with better controls. Pentax have caught up with the D7100... but sadly the D7200 is just around the corner. As for 1080/60p... I thought that would be a limitation of the processor. Then again, Nikon uses more or less the same processors as Pentax does, just with a new name (and some more input from Nikon).
The reason why Canon isn't doing great stills cameras for video below their Cinema EOS line is probably because that line is very lucrative. Sony... I'm sure they could do great, and maybe their APS-C/FF flagships will be, but they too have more professional video cameras they want to protect.