You can't really replace salt with substitutes directly to any significant degree, You'll be better served seasoning generously with other things.
For a first cut on my low sodium philosophy try http://www.cheftalk.com/t/63468/how-does-one-survive-on-a-2000-mg-day-sodium-diet
For sausage specifically, are you grinding your own meats? What tools are you using?
Take a look at this:
http://www.hubertkeller.com/recipes/recipe_details4d27.html?show=TV-Episode-221-A As it stands, it's about 250 mg added sodium per serving. not total sodium Guesstimating probably in the 500-600 mg range total. That's not a terrible starting point.
Lets cut out the added salt. Smoke or grill your own chicken seasoned simply with Mrs. Dash, or some Za'atar and ground sumac-- I use ground sumac a lot. Usually has a little trace salt added for the grinding, but packs a nice lemony flavor. Add a couple cloves of roasted garlic. Fresh garlic would be too strong for this particular sausage. Add some lemon zest, ground dried rosemary, or finely chopped fresh. A little cayenne or other ground chile of your choice.
I'd be tempted to add some grated parmesan for a little extra savoriness. It's salty, but you don't have to add a lot for good flavor impact. If this is right out, consider a few drops of good quality fish sauce such as Red Boat. Again, high salt but I'm talking about 5 drops or so in this whole mixture. less than 100 mg added sodium total. It will bring along with it a lot of savoriness and glutamates. It's often about using the very best sodium you can, not no sodium.
Mix, saute a little bit, and taste. This should give you an idea of any flavors you need to increase, called correcting the seasoning. Most often, this is about salt, but in our case, this is often about acid to help out the flavors.
His use of carrot is interesting to me in this especially. Besides the color and texture hits, carrot is one of the saltier vegetables. Not that it's risky for us in salt content as its still very low, but that it carries extra savory and sweet tones into this dish.
Consider some of the classic herb combinations. Above, I used Lemon, Garlic and Rosemary. These three go very well together. But you could tilt this in interesting directions with many others. Quatre Epices (Four Spice: pepper, cloves, nutmeg, ginger) Herbes de Provence ( savory, marjoram, rosemary, thyme, oregano--ofren lavender now in the US though I can't recommend lavender), even the Za'atar I mentioned earlier too. Garam Masala would be a fun twist.