Let's start with 100 years ago, to see how fast things happened. In the early 1900s we had just learned that you must wash your hands before you examine a patient, or help someone have a baby, or do surgery. Before that tens of thousands of people died of the infections that were on their doctor's hands. People were just beginning to use microscopes to see cells, and think how normal parts of the body, like skin and hair and blood were made, and how they were maintained for all the years of our life.
Now we have the tools to move the science very fast, but it still takes a long time to get discoveries in stem cell research to therapies. Part of it is that we didn't know how to treat people with the kinds of therapies that regenerated a diseased tissue for life; we're in a culture where we think drugs are the only answer, and the drugs are used up in our bodies in minutes to hours. You have to remember to take your drugs again every day until the disease is gone enough that the body heals itself (usually with stem cells). Back in 1945, the U.S. bombed civilian populations (people living like you and I who were not fighting in armies) in Hiroshima and Nagasaki, Japan with an atom bomb. The atom bomb kills by the explosion, kills by the fires it starts, and then keeps killing with radiation. The radiation kills stem cells, so after the bomb the people who got too much radiation couldn't make more blood (they got infected because the infection fighting cells are made from blood forming stem cells, or their blood wouldn't clot because they had no clotters called platelets, and so they couldn't stop bleeding). They couldn't repair their intestines (the intestines bring food to the body, and keep fluids in the body); with intestinal stem cells killed, their older intestinal cells died in 5 days, and with no stem cells, they are not replaced. No food goes in, lots of fluid pours out and the people got diarrhea that wouldn't stop, and so on.
This was a tragedy for these people and their families. Stem cell research was born then in an attempt to understand what had happened to their blood and their intestines, and doctor-scientists wanted to use that understanding to treat diseases. While that research started slowly, today stem cell research is going forward as fast as this government will fund it (which is, sadly, not very fast), and as fast as different states allow and oversee all kinds of stem cell research.
Now back to your question: How much will happen in a hundred years? I am confident that people with diseases of the blood will stop by their doctor's office and get a transfusion of blood stem cells, along with drugs to help the stem cells get to the blood forming organs. Very old people susceptible to infections because their blood-forming system is old will get a shot of stem cells from young people related to them (or their own stem cells taken and saved when they were young), and these stem cells will make the infection fighting cells that old stem cells can't. Children born with defective brain tissue will get shots of brain stem cells to repair them, or drugs that make their own brain stem cells grow faster and move to the places in the brain that need them. People diagnosed with all kinds of cancers and leukemia will have their cancer or leukemia stem cells (which are way different from their normal stem cells) isolated in the doctor's office, typed for the kinds of genes that went wrong to cause their cancer, and get treatments that kill the leukemia or cancer stem cells while sparing normal tissues.
Children who show the first signs of diabetes (they have to drink water all the time, and they have to pee it out many times a day) will get a shot of blood stem cells that have the diabetes genes corrected, and within weeks will be cured; no more insulin, no more checking blood for too much sugar every half hour. People who drink and drive and can't control their drinking will have the option to get a liver stem cell transplant with liver cells that takes the alcohol out of the body as fast as they drink it. People who have another disease that makes them build up cholesterol (a fat) in their blood and in the blood vessels will have the option of another kind of liver stem cell transplant, one that corrects the gene defect that allows cholesterol to build up.
These are not crazy science fiction stories. We could get there in even 20 years if we had the will to do it, and if we train the best young scientists who will do the research, and the best young doctors who will deliver the therapies, and if we didn't allow science to be halted by those afraid of the future and self-righteous enough to think the way they view the world should be imposed on the rest of us, even if we don't share their views. I hope you join us in helping stem cell research get us there.