Hello Juan
Yes, both backplane and switching fabric exist in all networking devices, including even the lowest-end devices. The switching fabric is essentially the integrated set of hardware and software resources within a switch or router that provides the logic, mechanisms, and architecture to switch data between ports. Even a 10-dollar unmanaged 5-port switch will have some level of software and logic circuits that comprises a switching fabric.
Also keep in mind that the backplane is kind of like the “motherboard” but it doesn’t necessarily need to be detachable like that of a computer. It may just be the circuit board onto which the port circuitry is hardwired. In any case, it is comprised of the hardware circuitry, whether detachable or not.
If the backplane fails, it really depends on the switch if you can replace it or not. For lower end devices, these are typically hardwired, so if it fails, the whole device requires replacement. Even for higher end devices, backplane is an integral part of the chassis so it’s not a trivial thing to simply pull it out and replace it. For modular switches, such as the Nexus 7000 or the Catalyst 9400, you can pull out and replace line cards. However, the backplane which is designed to be part of the chassis is not designed to be replaceable by the customer. If there is any failure, any replacement would have to be performed by specialized technicians.
The switching fabric is not a physical component but has a large logical (software) component so it is not replaceable in the same sense.
I hope this has been helpful!
Laz