I generally agree with Lad. Bishops getting canned is one thing, the laity is something altogether different whether it's legit or not. Excomunication in regards to the laity was only rumored to spoken of a couple of weeks ago. We'll see who runs and who stays. Much of this will depend on specific chapels and whether indult chapels are close by. I want to see if they take pics downs in the vestibules.
As I said, I spoke to fair numbers of them at our local SSPX chapel, and they were on the verge of pooping their pants over just the announcement that they WOULD excommunicate the bishops. I actually had to calm them down a bit by saying that 1) there's no excommunication for saying you are GOING to consecrate bishops, and 2) if they go ahead with it and do consecrate bishops, only the bishops are excommunicate, not the priests, and not the faithful, and 3) the worst thing that happens in such a scenario is that the priests who are subsequently ordained by them are "suspended", but then most Traditional priests are suspended already anyway. I believe that kept them from fleeing the chapel immediately, but 100% that they won't come within miles of the chapel this coming Sunday. Guaranteed.
Now, I can't tell you or even hazard an EDUCATED guess as to how many of this type there at SSPX chapels (and some of these were the CORE chapel members, those most active in helping out) ... but recognizing that SSPX had been luring in the reluctant and the fence-sitters for going on 10 years now with reassurances that their Confessions are valid (and of course Matrimony, provided that Presbyter Bob shows up), I suspect that there's a fairly high percentage. It may also depends upon which priest is in charge of any given chapel, where the old school types might have inculcated classic paleo-SSPX mentality among the faithful. There are some variables. But I fully expect the attrition rate to approach or even exceed 50%.
This Friday evening will be First Friday, and Saturday morning First Saturday ... and the lines for Confession are usually 3/4 of the way to the front of the chuirch (with confessionals in back), though the attendance is somewhat sparse. If there are many fewer in line for Confession, that would be the first canary in the proverbial coal mine, and then we'll have to see on Sunday. I fully expect that the wooden folding chairs will not need to be set up behind the last row of pews ... at the very least. But we'll see on Sunday. SOME of them might try to please "non-imputability", but that would a huge strech if they've read the announcement.
As for I, while I typically go to the independent chapel near me, I would like to make an appearance, have my brother take a picture of me while I drop money into the collection basket, hold up a picture of the consecrations while smiling and giving it the thumbs up ... and send it to Rome for consideration to be "excommunicated" by name.