What difference do blocking and non-blocking assignments have on a single-line assign statement?
The difference has nothing to do whether there is one one line or a block of code. If count is being read by another process synchronized to the same positive edge of clock, you have a race condition as to whether you're reading the new or updated value.
This code could be in the same module or connected to another module.
always @(posedge clk)
         zero = (count == 0);

Although synthesis treats this as &quot;zero will be true the the cycle after count is 0&quot;, zero might get ahead by one cycle in simulation if it reads the updated value to soon.
You should my recent post &quot;SystemVerilog Race Condition Challenge Responses&quot;