Creo Parametric 6.0 is scheduled to release in March (2019). This is shown on the PTC Product Calendar. I haven't heard anything about a Creo 6 sneak peak, but that doesn't mean one doesn't exist...
Product calendar only says it is planned for March 2019.
I would not hold my breath waiting for it.
They will sometimes update the calendar with an actual date, but only a week or 2 before anticipated release.
I got an email this morning saying it is released.
Product Calendar is not updated yet.
Software Download page does not have it yet.
It looks that PTC is updating the website. I'm making a trial version of creo, and automatically, it had updated to creo 6.0. So i'm starting using it.