Without the SSPX, I believe the TLM and Traditionalism would not exist today. Sure, God would have chosen others to heed the call and keep the finest traditions alive, but the SSPX was what the Lord chose.
The SSPX isn’t perfect, and perhaps relations with Rome could have been handled more smoothly - by both parties. However, without the Society, Traditionalism might not have the impetus it has now, if it even would exist.
However, I think it’s absurd, in a sense, to think that traditional Catholicism would not have existed - the SSPX is proof that Christ meant what He said when He said that the gates of Hades would not prevail against the Church. There is no such thing as the chance of traditionalism not existing, because Christ’s promise is enough to comfort us - and the SSPX is proof that our Lord means what He says