Anonymous currencies will be valuable without a legal intervention, if anonymity is lost then there is no future with its concept. Anonymous currencies are easy to operate illegally and also difficult to control, which is what this market encounters and it is difficult for governments to control it.
As a result of this I don't think that regulation will necessarily make anonymous coins more attractive to investors.
It's one of these things where the inverse of the common paradigm is true. Because if there is excess regulation in the field of anonymity, then there could be the worry that there will be a lack of anonymity within the coin as a result of governments dabbling with the ecosystem.
But at the end of the day some of these regulations are inevitable and can't be stopped.