<p>Management wants us to switch to Infragistics. But my boss says that any 3rd party is destined to fail, and at that point there won't be anything we can do about it.</p>

<p>Is he right, is he wrong? I don't know. </p>

<p>What are your opinions, is it better to use something developed inside the company, or do you prefer something like DevExpress, Infragistics, Krypton to name a few or is there something else even better that you would recommend instead?</p>

I don't think it's entirely bad to rely on third parties. Some are very reputable and will do a great job of supporting you. But on the other hand, some are terrible to work with even if they stay in business. I don't know anything about the frameworks you've mentioned, though.
Have you considered an open source framework? That way you can still work on it yourself if all else fails. Of course, you have to take into account licensing requirements when doing this, but I think it's definitely something you should look into if it's appropriate for the project.