> does the suspension make the current state in Germany similar to the Selective Service requirement in the US?

I don't know how the Selective Service requirement in the US works, so I can't answer this question.

> Or is it “easy” for the German government to establish a draft?

Such a (temporary) suspension can hypothetically terminated at any time by the government. The question is basically how the population will react. I guess if the suspension of the general conscription would be terminated by the government, there would be really furious public rallies (and I am rather certain that my boss would immediately attempt to approve a vacation request if I wanted to attend such a rally in Berlin if it happened during the work week - just as an "innocent" kind of support for this cause from behind the lines :-) ) because multiple generations got really radicalized against compulsory military service (I wrote about this topic at https://news.ycombinator.com/edit?id=46177817 ).

This is why the German government currently attempts to approach the whole topic of quitting the suspension of compulsory military service so indirectly.