Really? Like what? Gnosticism? Arianism? Calvinism?
Heresy is never vindicated, so if a schism is due to heresy, which SSPX has largely embraced, SSPX will never be vindicated. If the form of the liturgy is their only gripe, that, indeed, may be "vindicated", if only by universal indult. But SSPX claims that the so-called Novus Ordo canon is not valid and is, therefore, idolatry, is heretical. Many are sedevacantists. Neither of these reasons will ever be vindicated.
"Really? Like what? Gnosticism? Arianism? Calvinism?"
You're somewhat conveniently ignoring the larger schisms that have occurred, i.e. that between the Orthodox and the Catholic church, as well as the Protestant reformation.
Ultimately, I do think that both the Orthodox as well as the Protestants were somewhat vindicated in their positions. Were they right to schism? Not in my view. However, I might also note that several of the needed reforms of the church happened in response to schisms.
"Heresy is never vindicated, so if a schism is due to heresy, which SSPX has largely embraced, SSPX will never be vindicated. If the form of the liturgy is their only gripe, that, indeed, may be "vindicated", if only by universal indult."
You and I differ on several points. First, I believe that the underlying reasons for the SSPX schism has more to do with perceived heterodoxy in the western church than anything. I don't often like to get into the NO versus TLM controversy because I just don't have a dog in the fight. But I will point out that the transition was handled horribly. I think SSPX, particularly in the US, rose from legitimate grievances regarding that transition and widespread heterodoxy in the western church.
I find it interesting that you mention the indult mass. Do you believe that the universal indult would be being considered at this poiint or that indult masses would even be an option if there weren't an SSPX to force the issue? Or is it mere coincidence that the location of of many indult parishes is within close proximity of SSPX chapels?