Do you have to keep cutting your calories?

This is something I've thought about for a while, but never addressed it.

MFP gives me 1200 cals/day. That's cool. I've been sticking with that for about a month and a half with no problems. I've been losing the weight pretty slowly, but it's still coming off.

But my question is - will I keep losing weight until I reach my goal weight and the 1200 will be what it takes to maintain?

It just doesn't make any sense to me.....

Can anyone explain this?