I find the trick is to spin what I want to say into somthing positive. I can't lie but I can avoid the questions, or just be vague.

In this situation. "Will you miss us?" (assuming I won't)

"Perhaps we will have the opportunity to work together in the future" (not implying I actually want to)

"So long everyone!"(ignores the question, this may also end the conversation as youve given yourself an out)

"I'm sure I'll meet many new people at my next opportunity" (to them it may imply you where happy to meet them, even if you where not)