My, how OnePlus has evolved. You might remember that when it launched its initial device in 2014, the OnePlus One was only sold to those who were able to obtain an invitation. This was done to help the company better match up supply and demand so that it wouldn't build too many units. Invitations were given away through company-run contests and were also disseminated via the manufacturer's website. The company did away with invites in 2016 with the release of the OnePlus 3.
UPDATE: The video below, released today by OnePlus, shows the new logo. So we can consider the logo change to be official as of today.
In November 2018, OnePlus made a giant leap forward by launching the OnePlus 6T through T-Mobile in the U.S. This took the brand from being relatively unknown in the U.S. to one that was quickly gaining traction in the states. Last year, OnePlus added a "Pro" variant to the OnePlus 7 and this year we expect to see the company release the OnePlus 8, OnePlus 8 Pro and OnePlus 8 Lite.
With the company maturing, it has decided to change the corporate logo. A pair of filings with the U.S. Patent and Trademark Office (USPTO) reveals that the new logo will look similar to the current one but use a darker font. The USPTO filing says, "The mark consists of a design on the left and the word "ONEPLUS" in stylized lettering on the right. The design consists of an unlocked square with the design "+" in the upper right and the numeral "1" in the middle."
We would assume that the new logo will be unveiled as soon as this coming May on the company's new phones, all three of which should be 5G compatible.