halacha - Vegan tekheileth

Does the oral tradition that identifies the hilazon as the source of tekheles necessarily indicate that one could not create the indigo-colored wool by other means? The gemara certainly indicates that the color-equivalent, plant-derived kala ilan is not valid (e.g. Menachot 40a, 43a, Bava Metzia 61b) but it also implies that this particular dye was not as fast and permanent as true tekhelet (and therefore, implicitly, was not its molecular equivalent). If that is the case, if one was able to create a dye that was chemically indistinguishable from true tekhelet, considering that torah shebiksav (the Written Law) never explicitly mentions the source of tekhelet, might that not also be acceptable?