I would enjoy a mastering suite in Sonar that would have the functionality of that in Studio One.
To be able to layout the song order, have song edits update to mastering suite, and ability to apply a set of effects to a group of songs tied to a mastering section, and ability to add specific effects to specific songs within the mastering session, all while not leaving Sonar. 

Kind of like whats availabe in Presonus studio 1, Project Page (Mastering, DDP, Red Book CD burning, digital release). This would complete sonar for me.

merged with previous request

I think most people consider mixing, and mastering, 
two completely different skills,
requiring different setups and tools.
at least, i do.
 
possibly, by adding a 'mastering' section to the sonar layout,
it will diminish the MIX capabilities and selling points,
just to go into the market against well established mastering tools already available.
 
 

Not really, By adding a 'mastering' setup your reinforcing the difference between mixing and mastering. The studio 1 model is quite good. The ability to export a dpp image for replication or digital release would mean sonar has you covered from start to finish.

Yes, please do this. I don't want to buy Wavelab.

I don't think this selling point would hurt SONAR too much. The way I see it, a lot of people are already attempting to master their music in the DAW environment, whether it be with Ozone, Fabfilter, T-Racks or whatever. They are probably never going to buy or not even aware of Wavelab or SADiE or other mastering suites for that matter. Now I don't know if you would market this potential capability within SONAR to mastering studios, but I can definitely see this working with project and home studios.

I was reading another thread, I think it was the ddp thread in general discussions and Craig Anderton himself said he uses Studio One for his mastering.

I've mentioned before something about having a screenset [M] that sets up Sonar for Mastering, which brings up metering tools, and sort of changes the landscape to be more workflow conducive to a typical Mastering workflow, even one that can consider including external hardware.
 
What I didn't previously consider is, when you switch to the Mastering screenset, you can choose between Stems and Stereo (or eventually, Surround) to display your Master fader output or all your busses. There you could perhaps "bring-in" or process/export the audio from the Project in these two ways, so that you can also edit heads and tails, or run some analytical plug-in tools against the audio before printing or rendering. When I say, "Bring-In" I mean that, even though you switch to the [M] screenset, Sonar still has to process the audio as it would be played in the project itself. Trying to play back literally every track mixed down in Sonar to this screenset may not always be ideal. It may be best to use this as a separate Mastering tool, where you Import the audio out of the project and into this screenset, separately to save CPU and other resources while Mastering (especially since Mastering may use some real CPU hogging plug-ins!)
 
More, In the normal Export dialogue, we could see a check-box for: "Open in [M] Mastering Suite after export".
 
All of this opens doors to using Sonar for Mastering, and, in some cases strictly for Mastering, if the software workflow is good enough. If the Mastering screenset workflow is different from what Sonar uses natively, then it can be quite different in many ways, however, still included in Sonar and still integrated in ways we haven't considered. Throw in DDP, Master report sheets, CD-R track and sub-track markers, etc. and good metering and we could possibly see the prossible end of a certain other staple in the Home Studio market. To add, being able to "build" a final Master, as you can with Montages in Wavelab, is a very welcome thing for artists who want their music seamless from track to track. 

There seems to be two camps here.
1) mastering = the finishing of the material via a number of plugins getting the levels and sound correct
2) mastering = the setting up of the material for release on external media, gaps between tracks and adding metadata.

Sonar does 1) really well with the tools that come with it. For 2) Sonar needs to be supplemented with external programs or have additional features added.