Not sure if this is rumour or a leak, but…
Recently a interesting piece of art appeared in the world wide web. The picture seemingly shows the logo of a new Sly game for PS4 and Vita; if it is real or just a fake is as of now unknown.
The poster appears to state “Sly 5: Master of Thieves” with “PlayStation”, “PS4” and “PSVita” logos adorned in corners.
I wouldn’t get your hopes up just yet, but it’s possible that’s not a fake.