Watched the morning video again, stated Size of Device is the factor, all Windows device below 8 inches get the crippled Tablet/Phone UI, Where he showed a 8 inch that had Desktop mode and Tablet mode, They referenced Surface Pro 3 as a 2in1 device that would have Continuum Mode*, which can have a keyboard/mouse with a click. As Surface RT, Surface 2, all Surface Pro models all act the same (2in1), I think we will get Windows 10 RT with Office (not sure if it will be Office universal apps** or traditional Desktop (ARM Complied) Office*** like Office 2013 RT and with the Office universal** transition depending on Continuum mode*).
*Continuum Mode: On 2in1 devices, Windows 10 will move easily between keyboard/mouse and touch/tablet as it detects the transition and conveniently switches to the new mode.
**Office universal apps on Windows 10 offer a consistent, touch-first experience across phone, tablet and PC with new versions of Word, Excel, PowerPoint, OneNote and Outlook. Designed from the ground up to run on Windows, you can easily create and edit Word documents, annotate slides in real-time with new inking features or easily present PowerPoint presentations, and with new touch-first controls in Excel you can create or update spreadsheets without a keyboard or mouse.
***The next version of the Office desktop suite is also currently in development, more on this in the coming months.
Vlad-Stefan Nangiu stated on:
http://blogs.windows.com/bloggingwindows/2015/01/21/the-next-generation-of-windows-windows-10/
*It is our intent that most of these devices will qualify, but some hardware/software requirements apply and feature availability may vary by device. Devices must be connected to the internet and have Windows Update enabled. ISP fees may apply. Windows 7 SP1 and Windows 8.1 Update required. Some editions are excluded: Windows 7 Enterprise, Windows 8/8.1 Enterprise, and Windows RT/RT 8.1. Active Software Assurance customers in volume licensing have the benefit to upgrade to Windows 10 Enterprise outside of this offer. We will be sharing more information and additional offer terms in coming months.
So who knows now...