Luggage doesn't have to be checked through to the final destination, any in-between destination can be the final luggage destination - it is you to decide on that.

If, for any reason, the airline will reroute you (and you would miss your intended official intermediate destination) - you have the right to cancel the ticket anyway - no danger there (only danger is, that the original routing may not be available anymore for the price you are looking for).

Regarding the 'throw-away-last-flight-segment-portion' a 'very good friend of mine' would proceed as follows (without lying):

* right at the arrival point he would go to the airline desk (not a ticketing desk of that airline, just a 'transit'- desk and ask the airline for a refund of that last remaining segment, as unfortunately you are no longr ble to take that flight (as expected, the airline will then refuse).

* He will then, with tears in his eyes, regret and ask if at least he could delay that last segment (make it an open booking - and if the airline agrees may be forget about it forever)

* if still denied (as expected), he will then leave, not without saying, I am really in bad luck today, that you just have to cancel that last sement now, without me being able to take that flight.

(this is part of a post from the very early FrequentFlier board - posts: one of the guerilla-tips)