So, you probably don't need my advice, but I would say that the things I'm really interested in from Source Audio are those things that no one else is doing. I think the Hot Hand, Manta, and Multiwave Distortion are all truly unique products (I own the first two). These three products, I think, really bring sounds that almost no other products on the market can---the paradigm shattering of expression with the HH3, the integrated distortion of the Manta, and the unique sounds of the MWD. Which is not to dismiss the sounds of the Dimension, Orbital, or OFDs (and whatever else I'm missing), which I'm sure are great products (the OFDs and to a lesser extent the Orbital tempt me even though I mostly have dirt and modulation already well covered on my board).
All of that is to say, that's why I pushed my ideas earlier of a great synth and a great polyphonic pitchshifter. These are two products that only have a few variations out there on the market, and all of the existing products are limited or flawed in some way. That's why I would really like to see Source Audio take on these products, and those would be the products I would want to see ANY company take on. While I'm sure Source Audio could do great things with a delay, does the world need another delay? Every time I see a new delay on the market, I can't help but wonder what it provides that isn't already out there. To a lesser extent, it's the same thing with preamp modelers or some of the other ideas proposed in this thread. We already have more choices on the market than we need for these types of pedals. Source Audio could do what it does best and make a unit with unprecedented flexibility in these areas, but why not be even MORE unique and truly innovate with categories of effects that are not heavily represented in the market?
Despite the existence of this thread, there's a certain amount of arrogance (that's probably the wrong word, since it's all hopeful and well-intentioned!) for any of us to tell Source Audio what products they should make. It would be even more arrogant for anyone to try to tell them how to run their company...but I'm going to do it anyway.

I would say, be unique. Keep innovating. The guys in the company may have analog backgrounds, but you've clearly embraced digital, so you should continue to do the things that no one else can do with the architectures that you have created.
Just my $0.02, subject to serious inflation...