I found a good solution...
Here is the solution to have two different printer queues, one for USB and one for Wifi, for one and the same single printer. The solution is easy for Ubuntu 18.04. For my LL 5.2, it needs a little bit of daring administration:
1) Install Brother MFC-J497DW as USB as described above with the Brother linux-brprinter-installer-2.2.2-1. Say "N" to "will you specify the URI?".
2) Rename printer queue. That is easy with Ubuntu 18.04, but tricky with LL 5.2. I found it somewhere in the net: as Admin go to
/etc/cups/
a) Make a Backup of the file
printers.conf. In the file
printers.conf change only one line,
<Printer MFCJ497DW> to
<Printer MFCJ497DWusb>.
b) open directory
ppd and rename
MFCJ497DW.ppd to
MFCJ497DWusb.
Reboot and in LL Menu > Printers you will have 1 printer queue, i.e., MFCJ497DWusb. Fine!
3) Do step 1) again, but this time Say "Y" to "will you specify the URI?" and follow the instructions as already described in my top post and in
https://www.linuxliteos.com/forums/printing-and-scanning/brother-mfc-j880dw-can't-install-3611/msg27370/#msg27370. For scanner install use same ip address as for printer install.
4) Rename this new net printer queue MFCJ497DW to MFCJ497DWnet, as described above in 2), but of course use add "net" and not "usb".
You will now have the desired two printer queues one for wireless, the other for USB if the router is temporarily out of action, and both will print and scan like champions