While your point is mostly valid, the Planet of the Apes franchise has been extremely healthy lately and the Alien franchise is still doing very well, also (from a Box Office perspective). Night at the Museum is also a solid box office performer and would make for an interesting crossover with National Treasure. Percy Jackson, as mentioned is also something I see Disney as being interested in.
BlueSky Animation is likely to be sold off. Disney doesn't need them and they bring nothing but mediocrity to the table. The question is who is in need of an in-house animation studio? Well, what about streaming/online services like Netflix, Google, Amazon, etc? Same answer can probably be applied to the question of who is going to buy the RSNs.
Changing topics, Disney will now own the rights to the SW Original Trilogy (which FOX still holds). Maybe we'll finally get a re-release now that will undo what the 1997 re-release did.
Not quite sure that analysis is current though:
Planet of the Apes latest trilogy was certainly all profitable, but the latest, War, made $490 million which was a drop from Dawn's $710 million. Even if we discount that Dawn overperformed, War was the lowest performer in North America of the last 4 Planet of the Apes going back to 2001 at $146 million, which is at least $30 million below each of the others of the trilogy and the 2001 Planet of the Apes.
Aliens' latest iteration Covenant lost money with a $100 million budget (before P&A of probably around $40-50 million) against worldwide gross of $241 million (of which $45 million came from China). That's a fall from Prometheus which took $403 million worldwide.
Night at the Museum trilogy was all profitable, but again it's one of those that fell across each iteration to the point where the 3rd movie was barely profitable. The North America takes from the 3 movies fell from $251 million to $177 million to $114 million across the 3 movies. That's extremely unhealthy. Even the global take stagnated with China making up for shortfalls in other countries to hold the offshore take at $250 million.
Percy Jackson needs to be completely revamped (though Disney does apparently release the books, so they have an incentive to) with the movies costing around $90-100 million and each taking around $200-230 million worldwide. The latest also fell $20 million in North America from $88 million to $68 million. The profits are razor thin on these movies, so I don't see how they continue without a reboot.
We can basically see with most of Fox's franchises that reboots are needed. Even X-Men/FF need reboots looking at the various stages of production hell that some of that has gotten into as well as the general struggles of FF on the big screen, which is why this sale is timely in a general sense.
The Murdochs are, if nothing else, remarkably savvy about the timing with which they make decisions; they're selling looking at a bleak landscape when the value of their assets is at an incredible premium to the profitability and cash flows that they're putting off going forward. That's true for most of these assets for sale (except Star India and Hulu which have bright futures).
Of course, the reason Disney and presumably Comcast want these assets is that they have the heft to generate extra cash flows for the assets through streaming. The assets certainly are nowhere near the value of the price being paid right now.