Lululemon + Mirror cannot catch up Peloton
Lululemon's acquisition of Mirror will not enable to the company to compete with Peloton. It's much more difficult to add a technical hardware aspect to a softgoods apparel company than vice-versa.
While both Mirror and Peloton enable in-home fitness with hardware devices, the two are close to the same. Reviews of Mirror are somewhat tepid from professional reviewers, generally falling in the 3-4 star range. On the other hand, Peloton is generally highly rated, and notably, stands as the basis for which all other connected in-home fitness devices are measured.
If you know anyone that has a Peloton, you likely have heard anecdotal evidence of how much customers love Peloton. The company reportedly has over 850,000 subscribers. It'd be hard to get much anecdotal evidence for Mirror as there are only "tens of thousands" of recurring subscribers.
This acquisition brings to mind Under Armour's attempt to acquire their way into the tech startup market with acquisitions of MapMyRun. Of course, MapMyRun already had a large number of users and didn't need to drastically improve a large hardware device. Regardless, it hasn't exactly propelled UA into the echelons of Nike - or even Lululemon - as a fitness apparel brand.
Hardware products are notoriously difficult and expensive. It's much easier to add softgoods to a hardware product. Lululemon has an uphill battle ahead to making Mirror work and it looks a hill too big to climb.