Why isn't Eclipse SBT for NIOSII not available in Quartus 19.1?

Hi,

There is an change in replace Cygwin to WSL.

For question "Is Intel replacing it with some other Nios II Software Development Tools?":

No, there is no other Nios Softwrae Development Tools replaced.

For more information, you may need to refer to the document as link below:

https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/hb/nios2/n2sw_nii5v2gen2.pdf

Thanks