So, taking into account the two round of adjustment we've had from FDev so far, including today's, what PowerPlay activities still make some kind of sense to fit into one's gameplay, or should I just nip off into The Black for a month or two and explore like it's Update 14 and none of this ever happened?
There's still quite a lot left - nothing stand-out, but certainly a few left which can get something like 3k/hour and some others which can be used for opportunistic bonuses. Most of them are either already normal gameplay or easy to fit into it.
Bounty hunting is probably one of the better single actions, and should get a decent rate if you can find a good location, or be a decent bonus done opportunistically
Power enemy shooting is pretty good still but in most systems the main sources of them are the Power signal sources ... which losing S&R as an option hurts a lot. Still an option for contested acquisition.
Power cargo hauling is decent but in a ship of even medium size won't fill your hold, and most of the other short-range trade options are fairly weak unless you're flying a max-size cargo ship (inevitably for bulk cargo hauling, I guess)
Holoscreen hacking is a nice side option and can be easily fitted onto most builds but again you can't build an entire career around it, same with megaship scanning.
Odyssey Data
uploads and Goods theft should still work - you just miss out on a bit of efficiency by not being able to get merits for the downloaded data too. If you can manage to complete restore/reactivation missions at the same time, even better.
Mining is situational - because of the harsh location requirements - but in the right system could pay out pretty well if you were efficient at it.
(In terms of
merits gained any of those is likely to be better than the equivalent time spent gathering exploration data)