Add to the advantages of channel partners:
-Local knowledge of market conditions, regulations, business community and customs
-Expertise in certain verticals or solutions that tend to get lost in direct sales
-More of a "one-to-one" relationship for smaller customers who get put off dealing with Fortune 500 suppliers
Resellers go out of business all the time. They are mostly small, privately-owned businesses that sell out to other resellers as the principals retire, or fall off because they are under-capitalized, or they lose a couple key employees and their business goes south.
But lots of new resellers generally show up in the market to take the place of the departing companies.