The main approaches now are to accept that Vintage is the Lurrus format and diversity exists in the confines of Lurrus Combo vs Lurrus Value, or eliminate Lurrus as companion. People can play what they want and will play what they want, and indeed, the power of restricted cards can be pretty good at obscuring a decks flaws.
Vintage was in many ways already this type of format. Many decks were and still are heavily defined as if you have Force, Shops, Bazaar. It's all framing. No one ever looked at a shops deck and said oh your playing a non-bazaar deck huh? For all the nuance of specific card selections, many decks at there core were still doing the same things. Pitch Dredge and Sun Titan Dredge are still 2 separate builds, but at there core they are still basically the same.
Format diversity is worse in vintage more so than any other format pretty consistently since the dawn of the format. That is fundamental to the cards that are on the restricted list and the few that are surprisingly not. Most of the veteran players are not only ok with that, but actually strive to maintain it because they do not want radical shifts to the format. This is in large part why workshops has yet to catch a restriction but so many of it's pieces have.
However, Lurrus has been absurdly dominant immediately, taking 16/16 top 8 slots in both Vintage Challenges on MTGO, as well as winning both Paper Online events held in this weekend. As noted above, it doesn't appear from the data that other strategies are on par with Lurrus or that there is an emergence of viable countermeasures that exist outside of Lurrus decks.
Do we feel like this data is of a solid sample however. We really don't have a control for this type of analysis because we have never been playing under a pandemic with a set that is currently not available in paper. I also think that 1 month of results in the best of times is not enough to be sure, because new cards ALWAYS get used in high numbers at first.
Interestingly enough, I've actually just started running Lurrus in any maindeck that can support him mana-wise, but not as a companion, and has a fair amount of < 3cmc drops already. That's in Modern and Vintage. And he's just great whenever he hits. He's just insane valuetown. I actually find his lifelink to be the most annoying trait as you can't come out ahead in any way - even surprise chumping with snapcaster as a 1-for-1 gives them a free healing salve. There's just no stopping this card from being awesome, whether he's companion or a main deck value-engine.
This is actually undermining to the argument in the first place. If Lurrus is better maindeck as a 4 of then it would go some length to show that companion is not the issue, it's the power level of the card. If the card is too powerful as a 4 of the first step would be to restrict it. What if the ideal build for Lurrus is actually some copies main deck with a different companion in the board?