I secured my 45th region as the Scots in my first long campaign pre-patch and chose to continue - and yes, the new world can still be conquered.

Post-Patch I finished Portugal after claiming victory, I haven't played past this yet, but I'm pretty sure that the same triggers still apply.
I'd rather start a new campaign though because I'm hoping to be for once able to develop my empire before going on a massive war... in all TW games I've never gotten to the really good units simply because I was forced to conquer my neighbours or they just wouldn't let me be. Which meant that the border regions kept churning out the troops....

Anyway, I'm distracting from the original question, so nevermind ;-)