We already see this in old stuff. DOS games run great in dosbox, because the IBM PC was pretty simple. Same with the gameboy, snes, etc.
When you get to more modern things like Windows 98 games, PS3 games, xbox360 games... Most of those are much harder to emulate/crack/archive. They have more complex copy protection schemes, interact more deeply with their OS and hardware, and emulating them is generally more effort.
The next gen of stuff will interact with closed source now-defunct servers. Re-implementing those servers is very much possible... but a massive amount of effort. Effort that won't happen for most products ever.
The PS3 and 360 aren't actually harder to emulate because they have more complex copy protection; they're hard to emulate because they're very novel systems (hardware-wise) and developers had to use all sorts of tricks, which is something their successors are not.
Meanwhile, the PS4 is literally just a PC and already has a pretty good emulator (if early), because the PS4 has desirable exclusives. The author of it only started writing it a couple years ago and it's already booting commercial games and has a handful playable; way faster than old emulator development was! The Xbox One is literally just an NT PC and lack of emulation is largely because there's not really a point to, yet; it's just a PC and has very few exclusives.
The Switch is literally just a phone with a controller and had its first emulator booting commercial video games within the first two years, because it had desirable exclusives.
The Quest is literally just a phone (even moreso, because it's literally Android and even their window manager is just a layer over Unity). It isn't emulated or cracked because it has no really great exclusives and Facebook allows as much piracy as you want.
Windows 98 games are actually pretty easy to emulate; very little at all doesn't work with QEMU out of the box, and that heavy-handed approach probably isn't necessary for the consoles of the future; the PS4 has a great emulator that's basically just a compatibility layer like WINE is, because again, it's literally just a PC.
I thought it was because no had actually cracked the DRM yet.
It's also worth noting that plenty of emulators only work with homebrew titles early-on; a lack of a crack for the copy protection wouldn't in itself prevent emulation.
There's no point in doing it with the Xbox, because the Xbox has no exclusives anyone cares about and is more expensive than a device that sold tremendously better and is cheaper.
This is the same reason people develop private servers for MMOs, and the exact same reason they don't bother doing so for consoles if there's a better edition on another platform.
The niche of "cheap piracy box" has been filled, and the only way for people to have an incentive to hack on the Xbox while firmware updates are still going on is if it suddenly starts getting big exclusives now that it's EOLing.
There is an intrinsic economic incentive in breaking the console's security, because there's an untapped market of 50M devices out there already. If I have an Xbox One already, am into the idea of piracy (perhaps I bought my Xbox One near launch expecting the same kind of piracy scene the previous Xboxes had), why wouldn't I spend the cost of modchip?
There's a market for the kind of cracking and it's only because of the stupidily good job Microsoft did on the security that you're not seeing a homebrew or piracy scene (and thus not the seeds for an emulation scene).
Part of the intent on getting developers to use these APIs as much as possible is to make forward-porting / "legitimate" emulation of games easier.
DRM licenses are kind of expensive and it's hard to publishers to justify the added cost of DRM after the initial release, when they've made 80% of the revenue for the game. So they often (though, not always) get patched out eventually.
Most of the time an anti-DRM patch gets rolled out it's either a company/individual that has strong personal feelings about DRM (i.e. somebody like Stardock) or else it's a patch that the devs wrote way back when to make testing in some environment easier that they kept around and valid out of the goodness of their hearts. I think in almost all cases it boils down to someone who personally disagrees with the prevailing business opinion that DRM is good and actually has enough political power in the company to force their opinion onto the business at large.
It could easily be a perpetual license for a given title. Then there is no incentive to remove it.
But there's a business case to be made for patching out DRM very early in the product lifetime. The longer a product is protected by DRM, the more likely the DRM is to be cracked, and that this crack could be applied to a new releases. It doesn't make sense to put a new game release at risk just to keep protecting some five year old game from piracy.
If you're selling DRM, you want to disincentive publishers for using your protection for too long. And if the DRM is built in-house, you want it to keep functioning for a number of titles to amortize the cost of development.
You wish. NFSII for DOS was a HUGE task to run under DOSBox. Linux had it much easier with Wine on w9x games and DOSEmu for DOS games.
OFC games for the 486 and below ran pretty well on DOSBox.