Restyline (R) is very hot right now. I always confuse hyaluronic acid with hyaluronidase so excuse malpropisms. There will in future (and I have no doubt you know this better than I) be alternatives to R. Cosmetic surgery is very faddy. Patients read stuff on the net want the latest, competitors use new products to market their practises.
There is also a product with EU approval (can't remember its name, for some reason Bioactin C keeps popping into my head} which is a "bulk" filler and is easily reversible. The material when injected forms a thin crust around the central wad which remains liquid. The filler can be removed at a later date by introducing a needle into the core and extracting it.
Fat transfer or grafting is technique thats been in use for a very long time. It doesn't fall under any FDA guide lines. I would personally credit Dr Sidney Cohen of NYC for popularising the importance of loss of volume in aging and the use of fat as a correction. Credit for developing the new micro fat extractors I believe goes to Dr. William Little of Washington D.C. They are truly the important step. As they allow consistancy of delivery. The problem with the old fat was it was like catsup (a Bingham Plastic) difficult to control precisely and the risk of visable lumps was always present and very difficult to fix.