Toms is an annual, and when people graft a plant, it is always a perennial, a tree such as apricot, peach, or a rose. You could keep toms going by taking the sideshoots as cuttings; grafting Toms, I'm not so sure. But I'm no expert!
Firstly, vine tomatoes are perennials; they are just so prone to disease that we grow them as annuals.
Secondly, grafting tomatoes is not new; it has been done for decades, originally to overcome disease, with the rootstock being resistant, (often the fruit from the rootstock is inedible) but also, nowadays, to increase vigour.
Estamino, Submarine and He-man are well-known rootstocks