tl;dr: As long as you have enough USB ports available, you can still use your usb cash drawer if you decide to also add a usb printer at a later date.
Longer version:
If you are using the Square Stand for iPad, you can use both your USB drawer and add a USB printer later on. Both should also work fine in any other setup with enough USB ports. (For instance, using an on-the-go [OTG] USB hub with a compatable Android device.)
The only potential issue I can think of is if you want to use a USB drawer, printer, chip/nfc reader, and barcode scanner all at once with the Square Stand. The stand doesn't have enough ports to handle all four peripherals at once. In such a situation you'd either have to switch to a printer-connected cash drawer, or use a bluetooth barcode scanner, or use bluetooth to connect the chip reader.
The cheapest solution would be to use bluetooth for the chip reader. But then you'd need to plug it in for power somewhere, and you might discover connection issues frustrate the process. (This might not be a problem though. In my experience, the chip reader connection issues have pretty much been fixed by the most recent POS app update.)
Buying a bluetooth barcode scanner would be the most expensive solution. Plus it gives you batteries to worry about. On the plus side, if bluetooth is giving you connection problems my guess is that a glitchy scanner would be less frustrating than a glitchy chip reader, if you have to choose between one of them. And depending on the type of products being scanned and the setup of the sales area, the freedom of having a wireless scanner may be well worth the costs.
But I suggest buying a printer-connected cash drawer might be the best solution to the "not enough USB ports" problem. The printer-connected drawers are only about half the cost of the usb ones, so you'd likely be able to sell off your usb drawer and more than make up for the cost of getting a printer-connected one.
All of this only matters if you run out of USB ports though. If you're using no more than 3 peripherals with the Square Stand for iPad, or your other connectivity setup otherwise has enough USB ports, then you don't need to worry about it. Just plug everything in and the Square software should recognize and deal with everything fine.
