There is nothing to prevent any track from altering rules to allow other cars to race against fully legal VTA cars. Just realize that when running the VTA class this way you can detract from what has made this class succesful at many locations and it really becomes an outlaw class.
I would suggest to anyone who thinks a specific battery/motor combo is comparable to the current legal VTA options, to try it out at their local track and let us know what the results are. There may truly be better power options, but without some good data, many of these posts become redundant. Maybe 4-cell 13.5 or a 1-cell lipo in a VTA car is a good option. But would these other options need a FDR limit? Will they work well on a large outdoor track vs. small indoor track? Will they bring new racers or drive away old racers? Will they be inexpensive for novice and existing racers? Are they the same performance over a 5 minute or 8 minute race?
A point that sometimes is overlooked is that the creators of the USVTA rules did test various motor/battery combos to come up with the current rules. We can endlessly debate the validity of the choices, but it really doesn't add to the discussion without real world data. So suffice it to say that we should all know what the rules are at this point and that there are no current plans to change them. While it may seem a bit harsh (even though the intent isn't), having well defined rules that stay constant for an extended amount of time really helps the growth of any r/c class.
In case you need to locate the current rules, please see my signature at the bottom of this post.