As per the previous blog post about Microsoft Surface Mini and press event on the 20th of May 2014, there is a possibility of introducing a Surface Pro 3 as well along with the Surface Mini.
Microsoft has posted a support page on their site which mentions about a "Surface Pro 3 camera" and it also contains a discussion on how to add recording support for H.264 in Surface Pro 3. There is a possibility of it being just a typo, but on the other hand there are suggestions that Microsoft will be launching a fresh Intel-based Surface tablet on the 20th of May along with the Surface mini.
At the same time, CNET has reported during the last week that "there is definitely a new Intel-based Surface" which is planned to be introduced during the press event and it also indicates that the said Surface will include a new power-optimized Intel Haswell processor rather than another variant of Atom. Currently Microsoft uses Intel Haswell processors in the Surface Pro 2 tablets and they have improved its clock speed earlier this year.
Update to the above story: According to an earlier report issued by The Verge, they approached Microsoft to make a comment on the Surface Pro 3 and will provide an update regarding Microsoft's comment on the Surface Pro 3. The update on the matter was given by The Verge on the 15th of May 2014, indicating that the support page about the "Surface Pro 3 camera" was a typo. But it does not confirm that Microsoft is not trying to release a new Surface Pro soon, the only matter is that Microsoft does not want to discuss about it at the moment.
Images from: http://www.extremetech.com