We know the total number of skills in Skyrim is 18, Oblivion had 21.
For one, we know mysticism was removed, but effectively replaced with enchantment.
Blunt and Blade were replaced with 1h and 2h.
Hand-to-hand will probably fall under the 2h section, as the forms of combat have been condensed down to 1h, 2h, and marksman. Lowering the skill count to 20
From what we can see in the screenshot, Armorer was renamed into Smithing.
Alchemy was ported into the stealth section of skills.
Athletics and Acrobatics will probably be condensed down into a single skill. Lowering the Skill Count to 19.
The last thing I can think of to meet that 18 is the merger of Mercantile and Speechcraft.
Any thoughts or corrections on what I have said?
Here is my list
Combat:
One hand
Two Hand + Hand-to-Hand
Smithing
Block
Athletics + Acrobatics
Heavy Armor
Magic:
Alteration
Conjuration
Destruction
Restoration
Illusion
Enchanting
Stealth:
Alchemy
Security
Speechcraft + Mercantile
Sneak
Marksman
Light Armor