Apple isn't going anywhere. At worst, their smartwatch has mediocre sales like iPods do now, where the line is kept and maintained, but not actively updated like iPhones are.
I would say that the PC company that will be left standing is Apple in the consumer sector.
However, what isn't mentioned is enterprise sales. Businesses buy just as many PCs as individuals. In this market, I'd say it will be a tossup between Dell, Lenovo, and HP.
Dell isn't under the lash of the quarterly shareholders, so they can do what they well please. Charge off a quarter just for R&D? Dell can do that and not face shareholder lawsuits from the HFT guys.
Lenovo is China. They also can do what they well please because of the government/company interaction involved. They are not going anywhere because Chinese businesses need desktops, laptops, servers, and other items.
HP... who knows. They have a solid ground in the enterprise, but are shackled by being publically traded. However, their products are decent.
As for PC vendors, they just need to start realizing that the desktop is now a role that can be done by a tower, mini tower, laptop, tablet, or even a cellphone (as in the case of the Motorola Atrix). They also need to start adding functionality into their machines. A few examples:
1: There is a reason why NAS drives are hitting the market. Apple's MacBook and fast wireless connections are creating a market for NAS drives as well as larger servers for home use. Plus, backups don't hurt either, and file servers will only get more buyers as ransomware and other malicious software gets more common. There is a market here. For wired machines, sell iSCSI, 10gigE, and the ability to boot from the NAS (well, used as a SAN in this case.) One drive array then handles all the home files, and is easily backed up and managed.
2: Virtualization. Windows 10 is going whole hog with Docker containers, both "plain" and in Hyper-V VMs. It might be wise for EMC/VMWare to get with hardware makers and put ESXi into BIOS of computers before MS overruns the market with Hyper-V, or both players have to deal with OpenStack/Xen/KVM.
3: SAN functionality like snapshots, copying backups on the array level, deduplication, and other tools would be useful on PCs. Malware can't touch previous backups if done on the snapshot level.
4: Time to bite the bullet and move to SSD wholesale, at least for the OS. HDD bays are still useful, but the machine should at least boot, if not run its apps and data from SSD.
5: Consumer level backup media. Malware isn't going away anytime soon, and there is nothing out there that actually gives resistance from malware overwriting backup media, except for CD/DVD/BD-R drives. What would be ideal would be some form of inexpensive tape drive with the media able to be write-protected, maybe even WORM media available, so if some CryptoWall or CryptoLocker variant does its nasty work, stuff is still recoverable.
PC companies just need to open their eyes, perhaps move some enterprise features down the chain, and they will still have not just a market, but the ability to expand and get people to buy new stuff.