This has already been discussed in most of the home page "news" posts. (Ie. just go to the home page, read the posts and related comments)
Berserker has explained that it will be online only, but the game can be played as both single and multi-player; meaning for those who wish it, it will be the same experience as before. The game will be saved online, so even if your internet connection cuts out, or you change computers, you can play from your last saved point. You can also change from single to multiplayer and back again if you like.
The latest post from this week on the home page has Beserker suggesting an alpha release or pre-order may be made available this year so that we can test it out.