People seem to be judging mongoose on the d20 stuff they produced for Dnd 3E; thats not a propoer way of looking at it IMO. The best mongoose products and some of the best stuff for d20 was when mongoose applied the OGl to theri OWN settings.
Conan and babylon 5 for example, are two of mongooses main lines and some of the best selling d20 products published under the OGL. Lonewolf d20 was also fantastic. IMO this is what mongoose should keep doing; don't publish stuff for 4E, let the other companies do that. Use the OGL/SRD to publish for unique settings.
Sure this will be harder this time around, since the OGL is more limiting and does not allow all rules to be published in the 3rd party rulebook (thus requring the phb) but since other publishers will be focusing on producing strictly for dndn 4E, mOngoose will have a large niche market to themselves.
In many way's Mongoose is like TSR at its height (or close to it(; they have fantastic settings, and they go all out to support them (B5 novels are being published, Lonewolf gamebooks are being republished, etc all by mongoose) Mongoose is also AFAIK the 3rd largest poublisher, after WOTC and WW.
Furthermore Mongoose has made a significant investment in its future by purchasing the Runequest and traveller rulesets, so they truly have the luxury of sitting back and deciding what they want to do, rather than what they have to do to survive.
And as always, mongoose fans (messageboard readers) were the first to hear of their plans. Say what you will about mongoose, their link to their fanbase is topnotch. Sometimes msprange just goes onto his boards and asks the fans what they want in an upcoming product, or which way they should take a certain product line. And then does exactly as the fans suggest.
However, mongoose needs to reemphasize quality. Their editing has improved, but it needs to be taken a step further. Also, they need to cut down on quantity and focus on quality (to a profitable extent anyway) they are already doing so from what I have seen oiver the last few months however.