In no particular order. Hope to add more whenever I think of something. Just needed a place to gather these.
- Work with FilmLight, Nucoda, Autodesk, etc. to implement and support AAF to the point where resizings, reframings, repostions etc. travel across to their conform and grading applications. Would save hours of time for their users and for us.
- 16x9 frames in Scripts
- Editable Scripts inside MC
- Allow Target Masks option in Export
- Allow Target Masks with 3rd party I/O
- Add audio bussing so that one can apply effects to dialogue / SFX / music groups and export stems
- AAX support
- Keyframeable RTAS (and/or AAX) plugins
- Allow the use of multichannel unwrap or multichannel reverb on stereo tracks (currently, it doesn't work because a stereo channels only has two voices to send outputs to - adding a stereo-to-surround unwrapper has nowhere to go with its 6-channel outputs).
- Fix the Audio Tool window, still a mess, even in v7. Not enough resize options, no logical default sizing.
- Allow me to hide/skip/kill the 'Live' mixer. I toggle between Clip and Auto all the time, and have to click through Live for no good reason. Also, make the switch between Clip and Auto something I can map from the keyboard.
- Allow all new features to be turned on and off through mappable buttons/keys (unlike you did with Smart Tool, Auto/Clip/Live, Target Mask).
- Automation Gain with an auto-record mode when used with Artist Mix or Artist Control faders.
- More useable buttons on Artist Mix.
- Recognize 5.1 and 7.1 mix files from Pro Tools. Meaning that if I get a set of files labeled FinalMix.L.wav,m FinalMix.C.wav, FinalMix.R.wav, FinalMix.LFE.wav, FinalMix.Ls.wav, FinalMix.Rs.wav, I expect MC to recognize those extensions and offer me to import as a 5.1 clip.
- Allow us to export multiple monophonic BWAV's for a surround sound mix. Now it can only be an interleaved BWAV, limiting the duration of such an export.
- Fix traditional BWAV import. All per-channel metadata should import, all iXML metadata should import. Enough with the workarounds and limitations. Forget BWF import over AMA, it makes no sense. Just make sure that everything works with the common files from Zaxcom Deva, Aaton Cantar, Sound Devices 7-series, Zoom, and what not, including all the metadata they write in any form they write it.
- If you do insist on BWF through AMA, allow PerfSlip on AMA'd clips.
- Allow Perf Slip in all non-film projects.
- Allow offsets in AutoSync.
- Allow us to send a timeline element (clip/segment) to just the LFE channel without having to pan the same element to any of the other channels. Especially convenient when you get separate mononphonic elements and need to pan each track to a dedicated output channel.
- A less crude Find / PhraseFind interface, with more options to search footage.
- Source Sequences or Selects Sequences. Meaning the option to build sequences with selects or stringouts that act like subclips. Allow matchframing back to these selects sequences (or stringouts or whatever you call it). But DO eventually allow us to link to the original clips ("commit selects to originals").
- Give us properly kerned fonts for the Timecode Burnin. Clip names and sequence names as well as numbers look terrible. 
- Properly scale Generator effects (SubCap, TC Burnin) - currently they do not scale proportionally when switching between SD and HD.
- Allow partial italics in SubCap (often used for V.O. and off-scene telephone dialogue).
- Fix SubCap performance. Sequence with 1200 SubCaps should play over two layers of video, a color correction and a mask without having to render first (this is especially true on Nitris DX systems - software-only is much faster).
- Allow hard returns in the SubCap text editor without the need to open the Master Caption List.
- Fix the cut-off lower part of SubCaps.
- Faster saves, background saves, instant saves, save everyting all the time (like Lightworks). No more waiting for bars.
- Background rendering. Preferably of one or more preselected tracks (e.g. let me background render V11, where I might put my overall master grade or mask).
- Fix Universal HD Mastering so that it has ALL the features of the classic Universal Mastering in the SD days.
- True, proper file-based Universal Mastering.
- Improve anything in the (Symphony and/or MC) color corrector, one with useable secondaries and windows would be nice.
- Allow Symphony's relational CC on user-defineable metadata, not just tape/clip/subclip. File-based world needs more flexibility.
- Resolution independence.
- Color spaces besides Rec 709. Don't forget Rec 2020.
- Bring back mouse jog/shuttle on non-DX systems.
- Allow jog with DJ-sound (not scrub) on Avid Artist Transport.
- Rename the RGB and 601/709 selections in Import and Export.
- Turn on realtime SD downconversion of 1080/24p projects using 24p PAL pulldown (as available in an SD PAL24p project).
- Offer an MC and Pro Tools bundle option, give users of one a small discount when getting the other.
- Consolidate the way you license MC and PT and the various options. I now have dongles for MC and Symphony and Interplay options, activation codes for ScriptSync and PhraseFind, license codes for BCC, iLok for plugins and Pro Tools.
- Fix the tearing video in the source/record monitor and in FSD.