More specific:
Let's say I buy this 8 speed Sora 3300 RD
http://cgi.ebay.com/Shimano-Sora-330...item27b0007208
But my freewheel right now is only 5 speed. Will my friction shifters work with this? I feel like if I am getting a new RD, I might as well get one that can accommodate some future upgrades (to a 8 sp freewheel and/or indexed shifting) that I might want.