That's what they're speculating, that's speculation only.
( ( That ( 's ( what ( they ( 're speculating ) ) ) ) ) ( , ( that ( ( ( 's speculation ) only ) . ) ) ) )
(ROOT (S (S (NP (DT That)) (VP (VBZ 's) (SBAR (WHNP (WP what)) (S (NP (PRP they)) (VP (VBP 're) (VP (VBG speculating))))))) (, ,) (NP (DT that)) (VP (VBZ 's) (NP (NN speculation)) (ADVP (RB only))) (. .)))
That's hard fact, not speculation.
( That ( ( ( 's hard ) ( fact ( , ( not speculation ) ) ) ) . ) )
(ROOT (S (NP (DT That)) (VP (VBZ 's) (ADVP (RB hard)) (NP (NN fact) (, ,) (RB not) (NN speculation))) (. .)))