There are some IRS cars capable of going 8's. The ones I've seen the most are GTRs, Supras, and the occasional 2JZ/LSx swapped 240sx (I think they swap a Nissan/Infiniti Q45 rear into it or something).

Now that the 2015+ Mustang has IRS, I expect to see more of them as well. I think there's already one in the 8's.

But yeah, IRS is a major pain at that power level. Most (all?) of the performance cars today have IRS, so I expect improvements to come.