Hopefully, with the M-3's being put back into service for a while, we will get some head end videos of the new third track, the double track to Ronkonkoma, the mid Sufflok yard, the new interlocking into the Oyster Bay branch, Harold interlocking changes, the mid-day storage yard at Sunnyside, and the tracks into Grand Central.
I really hope you're right but I don't think they're going to be running that many M3 trains and the odds of catching one will be slim at best. And don't forget that the storm door windows may be fogged up to the point you can't see out of them.
Another possibility is that they'll just run them on the Brooklyn shuttle trains and insult the Brooklyn riders a little more.