I talked to Lead Designer Damion Schubert about Legacy Level 50 and potential rewards, and here's what he said:
We are currently looking at things we can add to the Legacy page - in particular, Legacy will need some juicing up after the Cartel Market goes live - but I wouldn't expect any changes until after the Free-to-Play update at least.
Thank you for informing us.
I also think that legacy needs some major buffs, mainly due to the fact that everything requires money... I have lvl 37 legacy and I have barely bought any of the perks..