It isn't, of course.
( It ( ( ( ( is n't ) , ) ( of course ) ) . ) )
(ROOT (S (NP (PRP It)) (VP (VBZ is) (RB n't)) (, ,) (X (PP (IN of) (NP (NN course)))) (. .)))
It isn't now, but it could be possible in the future.
( ( ( ( ( It ( ( is n't ) now ) ) , ) but ) ( it ( could ( be ( possible ( in ( the future ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (PRP It)) (VP (VBZ is) (RB n't) (ADVP (RB now)))) (, ,) (CC but) (S (NP (PRP it)) (VP (MD could) (VP (VB be) (ADJP (JJ possible) (PP (IN in) (NP (DT the) (NN future))))))) (. .)))