Odds of Hanging On
You can probably stay in this field for a long time, but you might not stay in one particular lab for long. The key to conducting stem cell research isn't so much the research part as it is the finding-money part. A lot of stem cell research depends on grants from a variety of government, public, and privately-owned grafts. If federal funding for the kind of stem cell research you do dries up, be prepared to join a team of, say, Danish researchers instead. Stay flexible, stay employed. That's the motto.