I can speak to that.
Without question, researchers are working with all of these cell types. We need to compare and contrast them. And they're being used for different types of therapies. So iPSC will not replace everything else, and neither will embryonic stem cells be used for all possible trials. We're talking about hundreds of different diseases with multiple solutions. The best solution for each disease may well come from using different types of cells.
These drug screens that I talked about are making using iPSC cells. The Geron trial is making use of human embryonic stem cells. Cancer stem cells are being derived from tumours to develop cancer treatments. Mesenchymal cells are being used to modulate the immune system.
So there's no one solution, and one particular cell type doesn't fit all sizes.