That's technically correct (the best type of correct!), but without speculation, the CPU can't see beyond a branch, so the window in which the machine can reorder instructions is very small. (For x86 code, the usual rule of thumb is that branches occur once per 5 instructions.) So in practical terms, an OoO design (in the restricted-dataflow paradigm, i.e., all modern general-purpose OoO cores) always at least does branch prediction, to keep the machine adequately full of ops.

An interesting question, though, given that we're going to do speculation, is what types of speculation the core can do. The practical minimum is just branch prediction, but modern cores do all sorts of other speculation in memory disambiguation, instruction scheduling, and the like, some of which has enabled real side-channel attacks (e.g., Meltdown).

Also, FWIW, Pentium was 2-way superscalar, but not OoO in the fully general dataflow-driven sense; the Pentium Pro (aka P6), in 1995, was the first OoO. (Superscalar can technically be seen as OoO, I suppose, in that the machine checks dependencies and can execute independent instructions simultaneously, but it's not usually considered as such, as the "reordering" window is just 2 instructions.)

OTOH speculation without OoO Is not only possible but in fact very common. For example the majority of non ancient in-order CPUs.

In fact the original pentium, contrary to your statement, was an in-order design (the pentium pro was the first Intel OoO design). Also I believe that 486 already had branch prediction. Pentium claim to fame was being superscalar (i.e it could execute, in some cases two instructions per cycle), a better FPU and better pipelined ALU (I think it had a fully pipelined multiply for example).