Refinement for sure, and some nice modelling, but no shocking news
We have known about the statistics of supernova explosions from watching similar galaxies to ours (spiral or barred spiral, not lenticular BTW) for a long time. I myself have seen half a dozen in the last three years in various "nearby" galaxies with my humble 8" scope (none discovered by me, I just watch the ones others have found), so the statistics that have been gathered with big scopes are pretty good. We know that a naked eye supernova is long overdue, but that does not alter the probabilities of having one going off now, or in the next few decades.
The authors do provide nice estimates of the brightness distributions expected, however, I do not want to knock their work.