Honored Contributor
Honored ContributorNios II supports the Nios I SDK so there really isn't any reason for you to use Nios I.
As you point out, you could stay with Nios I for many years without any problems but you'll be more on the mainstream if you switch to Nios II. One of the great things about the Nios I and Nios II soft cores is that we just use normal VHDL/Verilog and Quartus synthesis so supporting a variety of FPGA devices is pretty straightforward. Altera is pretty good about having new devices be compatible with old ones so you should have few problems migrating Nios I or Nios II to newer FPGA devices as they become available. This is one of the advantages of soft-core CPUs over hard-core CPUs on FPGAs. Given all this, I must say that our focus at Altera is now on Nios II development. Nios I is basically in maintenance mode with bug fixes.
