Technically possible, but any future update will need to have its hashes calculated to properly detect what version you are running.
However, It is not intended that way. The installer is meant to make it easy for non-savy users, or lazy ones like me who either has to make CPU bakes now and then, or install GPU in many computers. Theoretically, you can “clone” the installer’s github repository, then each time I upload a change you can pull the changes, but not automagically.
If there is enough interest I may look onto something like that, but would depend on the use case and the free time I have available. Also my guess is this won’t take long to get integrated into the engine (this is amazing tech). At this point anyway I don’t believe there would be much more updates before 4.21 starts previewing, at which point we’ll probably need another GPU heavy update, including the batch file, or even (hopefully) see some GPU baking integrated into the engine which will make the installer obsolete.