> However, a lot of times the "want to do it forever" part could be a sign that the candidates doesn't want to learn anything new, which is indeed a very bad sign.

While that is true for a lot of jobs, there are also a fair number of employers that are perfectly content to have an employee that does job X at their company for as long as they are of working age. In the software world it pretty much follows from the fact that the largest chunk of development jobs out there are just CRUD apps and processes that feed them. Many companies do the same things with largely the same software for years and years and years. As long as an employee is getting the work done, many of those employers are thrilled to have a long-term employee doing the same tasks they've been doing for years.