What's the one feature that many Microsoft Surface Pro 3 owners wish they had on the hybrid laptop/tablet device? It's 4G LTE availability, and rumor has it that Microsoft is adding in the cell functionality to the upcoming Surface Pro 4.

With the integration of cell capabilities to more tablets these days, it only makes sense that hybrid devices would start getting cell service, too, especially if both an LTE version and a less expensive wi-fi-only version were both offered. But this isn't the only rumor surrounding the Surface Pro 4.

First off, it's inevitable that the new product will enjoy a redesign, but how drastic will that redesign be? A higher resolution display would be a welcome start, although the Surface Pro 3 is already equipped with 2160 x 1440 pixels. But it all really depends on the size of the display, too. Speculation is out that a smaller 8-inch model will be offered for portability's sake, right along with a larger 13- or 14-inch version. The 8-inch version would be called the Surface Pro 4 Mini, and would also cater to those looking for Surface Pro quality with a smaller price tag.

Intel's new Core M processor is expected to power the Surface Pro 4, which will be a big step forward with its fanless operation and cooler running temperature. The RAM is expected to hit 16 GB and run on the brand new Windows 10 platform that will revolutionize that bridge between mobile and desktop computing.

In a recent earnings report, Microsoft says that its Devices and Consumer group's revenue grew 8 percent in the last quarter of 2014 over the same time last year. While much of this has to do with the success of the Xbox One, much of it also has to do with the somewhat unexpected popularity of the Surface line of products, thanks to the Surface Pro 3. The tech company also notes that revenue for the Surface line rose 24 percent since last year.

So the big question is if Microsoft can meet and beat those sales figures and revenue earned with the Surface Pro 3. The new Surface Pro 4 would need to not only continue to impress those who already enjoy the current Surface Pro 3, but also win over customers from the expanding mobile computing market that may already be hooked on another brand.

Higher specs, more screen choices, and cell capability will all definitely work toward that goal, but price is also a major factor to help get the product into mroe hands while still earning the company that revenue it has been enjoying.

While no price has been announced, some experts believe that the larger 13- or 14-inch model will retail for $899 while the mini model with an 8-inch screen will go for around $599 to give a better range of options than the Surface Pro 3 currently offers. The Surface Pro 3 in its lowest model goes for $799 while adding the best features will run it up to $1399.

Right now, there is no official release date for the Surface Pro 4, but many believe it will launch at the end of 2015 right along with Windows 10.