I love my Surface Pro 3.  Windows 10 has transformed it from something I occasionally fiddled with to my primary mobile device (replacing my iPad and MacBook Pro combo for trips).

But it is, by no means, perfect.

The weaknesses of the Surface Pro 3 include:

1. It is almost 1.8 pounds.  That's really too heavy to use as a tablet for an extended period of time.
2. While Windows 10 has greatly improved the issue of it getting hot and the fan blariung, the fact it has a fan means extra weight and noise.
3. No LTE.  I always found that astounding.  I keep my iPhone with me at all times anyway but it's kludgy to have to connect to it from my Surface while traveling.
4. The power connector is obnoxious and expensive. 

So what would my dream Surface 4 be like?

1. Less than 1.4 pounds
2. 13 inch screen
3. No fan
4. LTE integration
5. USB-C based power.

Note I made no mention of the CPU speed.  That's because the Surface Pro 3, with its 3 year old Core I5 in it, is fast enough for all my computing needs.