Many of us do "frameserving to Handbrake" to achieve MP4, with x264 video encoding; aac audio.
This should be a Render option direct in Vegas Pro.
Ideally Multi-Core CPU or GPU (optionally) accelerated.
Other free (Handbrake) and commercial software (like Mercalli and TMPGEnc) offer x264 rendering.
Yes, .265 is the future, but x264 is the gold standard on current devices, tv's, Youtube, etc etc.
Wide Compatibility, 4k support and small file sizes will make mp4 / x264 / aac needed for years to come.
Please add to Vegas Pro.
Should be a quick and very welcome feature add to Vegas Pro.
Thanks.