"In the short term, these micro-robots could be used to deliver cancer drugs (or any kind of medication) in a highly-targeted fashion, rather than the carpet bombing approach that is currently used" You can almost always find the cancer therapy tie-in with these kinds of things. In this case "near term" would be 15-20 years at best. Getting stuff inside of cells without the immune system going caveman on your nanobot…
Inside cells? That certainly is way off - but things like getting chemotherapy drugs mostly to the organ or body part that is cancerous should be much easier.
There is some success using antibodies to deliver targeted therapies to certain organs, but in general, this drug delivery is a very hard problem. If we were able to solve it, then we would easily cure cancer. There are tons of chemicals that are toxic to the body as a whole, but would work great if you could narrowly target to the tissue or cells of interest.