I respectfully disagree. It might be true in some sense of maybe thats what some in Reform's inner circle want, or what some of their big donors want, but its not what the party as a whole wants or stands for, which includes its candidates and the membership. Its certainly not what most of the people who vote for it believe. The people who are voting Reform, and even members and candidates, do not share those beliefs. They dont have any consistent beliefs between them about pretty much anything other than immigration.
I have seen Farage's success coming. I think its been on the cards since pre-Brexit. I think a large % of the population are not happy with immigration levels and they feel strongly enough that they will vote for what is little more than a single issue party. My main belief, which I've been banging on about since the Brexit vote, is that the major parties (and media) have not dealt with the topic effectively.
Now, I get that what you actually mean is that I haven't seen the rise of an extreme white nationalist, extreme libertarian, fascist-style party that seeks to serve the interests of the wealthiest people in society. I get that you mean Reform actually stands for those things, regardless of whether or not its what Reform voters believe. But I'd argue that a political party is its members/core voter base and the shared ideas. There may be some senior figures in Reform who are white nationalist, libertarian, fascist extremists, but if that's the case then they are just using Reform as a vehicle, and they will switch vehicles when and if required or when the current vehicle no longer suits their needs. I dont think they will be able to transform Reform from what it currently is - a single issue anti-immigration party - into a party that is anything broader, because the membership would just split into different groups (like Rupert Low). The Conservative Party in contrast survives throughout decades/centuries despite different factions within it, because it fundamentally has a core ideology that remains present.
I think the only way to stop Reform in the near future is for the left (heck, even the center or Tories) to communicate better to the public about the single issue that is currently causing Reform to win votes. The current way it is approached (and has been for 10+ years) isn't working and will never work.
Long term, Reform will stop itself. It will exhaust it's current source of fuel and at some point it will no longer be relevant. It exists only in the here and now. It wont survive through the centuries like the Tories because its empty at its core. Long term I'm more worried about what will come after Reform, because it could be something even worse.