I reckon it will go something like this:
203-205: 90 Minute Filler Episode
206: Kakashi Gaiden
207: Kakashi Gaiden
208: Kakashi Gaiden
*END OF SEASON 8*
And season 9 will be the start of part 2.
Of course that's just a guess, but if you go by wikipedia season 8 should definitely finish with...
