Sasuke's short encounter against Madara is not really a valid indication (Madara is way too powerful for Sasuke alone to face him or even give him trouble in a straight fight so it's not that surprising) but, what your point is possible.
Hashirama giving Sasuke a way to stop Madara could mean two things :
- either Sasuke already started the plan before rushing to face Madara the way he did, and i might not like Sasuke but, i know that he's not that foolish (don't like this scenario/doesn't make sense, it wasn't a CLONE/Genjustu).
- or Sasuke is seriously injured/on the verge of death (the obvious/clear explanation) and AFTER he recovers from his injury (probably the man in the last scan in the last chapter will help him) he will use the power Hashirama gave him.
i'll say it again Sasuke is no match for Madara in a straight fight so his quick defeat is no surprise really :yeah: