I haven't tried to change money, but I'm betting it will be back if it is gone widespread.
Most likely, there were no pesos because the banks were closing down for the holidays, I'd bet. The arbolitos (the guys who do the money-changing for the most part) get their money from the cuevas (who are the big-money guys). The cuevas get their money from the banks. I've often had issues if it was near a holiday and a lot of guys have been out of pesos.
As far as the massive raid goes - if it happened, it's been happening on and off for the last couple of months anyway. I mean big raids. They've been trying to keep the blue rate down for the last couple of months and they were using the raids as part of the "convincing". It's after the holidays and they may be trying to remind people that they don't want the blue rate to go so high, which it was probably likely to do.
If the government has actually found a way to shut down the cuevas, then I'm outta here, to a place more congenial to reality, like Paraguay. Hell, I'll leave my apartment, furniture, everything and get out of this crazy place.
But I don't think that's the case.