I recently contacted HTC and Sprint about any possible updates to my EVO 4G here's what they have to say
Dear (MY NAME),
Good question, (MY NAME). I would be more than happy to provide you with as much insight as I can.
All I can really say for sure is that the Evo is going to get an update of some sort to, at the very least, address a few issues with the last update (streaming media, battery life, and a few other problems that have arisen). I have a feeling that this may end up taking a while, since we're thoroughly investigating the battery drain issue, and we want to make sure that it's 100% resolved, prior to releasing another update for the phone. You can, however, follow us on facebook (HTC | Facebook) and twitter (HTC (htc) on Twitter). Once that Evo update is ready, we'll definately make an annoucement through both of these websites, as well as HTC.com.
Will this update contain the the latest Sense UI update? It's tough to say, a lot of carriers prefer not to share a full list of enhancements with our technical support reps, as they prefer to go for the surprize approach. I would imagine that with the Evo being Sprint's first 4G phone that in order to remain competative with Verizon's Thunderbolt and AT&T's Inspire, I can only really _guess_ that the Evo will eventually see the latest Sense UI (not only that, but speaking from personal experience, the Evo is the phone that we recieve the most request for the latest Sense UI). Bottom line, though; this is something left up to Sprint. We've forwarded many suggestions and many requests for this enhancement, so Sprint knows that interest for this exists.
Can't make any promises, but from what I've seen, I remain optimistic.
Thank you for taking the time to contact us, (MY NAME).
We are always happy to be of assistance. Keep in mind that we are here to answer any questions or concerns between 6am to 1am EST, 7 days a week for your convenience. You may also visit us at HTC - Mobile Phones, Smartphones, Cell Phones, PDAs and Site URL not found for further assistance.
To send a reply to this message or let me know I have successfully answered your question log in to our ContactUs site using your email address and your ticket number (MY TICKET NUMBER).
Sincerely,
(THE PERSONS NAME)
HTC
EDIT: I also asked about Gingerbread but she dodged my question
So far I have yet to get a response from Sprint
Dear (MY NAME),
Good question, (MY NAME). I would be more than happy to provide you with as much insight as I can.
All I can really say for sure is that the Evo is going to get an update of some sort to, at the very least, address a few issues with the last update (streaming media, battery life, and a few other problems that have arisen). I have a feeling that this may end up taking a while, since we're thoroughly investigating the battery drain issue, and we want to make sure that it's 100% resolved, prior to releasing another update for the phone. You can, however, follow us on facebook (HTC | Facebook) and twitter (HTC (htc) on Twitter). Once that Evo update is ready, we'll definately make an annoucement through both of these websites, as well as HTC.com.
Will this update contain the the latest Sense UI update? It's tough to say, a lot of carriers prefer not to share a full list of enhancements with our technical support reps, as they prefer to go for the surprize approach. I would imagine that with the Evo being Sprint's first 4G phone that in order to remain competative with Verizon's Thunderbolt and AT&T's Inspire, I can only really _guess_ that the Evo will eventually see the latest Sense UI (not only that, but speaking from personal experience, the Evo is the phone that we recieve the most request for the latest Sense UI). Bottom line, though; this is something left up to Sprint. We've forwarded many suggestions and many requests for this enhancement, so Sprint knows that interest for this exists.
Can't make any promises, but from what I've seen, I remain optimistic.

Thank you for taking the time to contact us, (MY NAME).
We are always happy to be of assistance. Keep in mind that we are here to answer any questions or concerns between 6am to 1am EST, 7 days a week for your convenience. You may also visit us at HTC - Mobile Phones, Smartphones, Cell Phones, PDAs and Site URL not found for further assistance.
To send a reply to this message or let me know I have successfully answered your question log in to our ContactUs site using your email address and your ticket number (MY TICKET NUMBER).
Sincerely,
(THE PERSONS NAME)
HTC
EDIT: I also asked about Gingerbread but she dodged my question
So far I have yet to get a response from Sprint