About the same as Yahoo being bought or partners with Ford in car making, bought or partners with Apple in hardware, bought or partners with Microsoft in software, bought or partners with McDonald's in food, bought or partners with Starbucks in coffee.
ANYTHING is possible with Yahoo! and Alibaba.
a) Alibaba buys out Yahoo! for $xx a share (I would bet $40-50/share) and reclaim their full ownership
b) Alibaba and Yahoo! partner to bring Alibaba services to Yahoo! and the Americas and Japan
c) Yahoo! licenses Alibaba technology / payment portals, etc
d) Alibaba goes IPO and Yahoo! benefits in cash money (IPO $100B+)
(After IPO Yahoo goes and purchases some cool new companies that add revenue)
f) Tumblr is monetized and Alibaba promotes/licenses Tumblr in China
g) Yahoo! Search is improved and revenue increases with Tumblr/Alibaba ad revenue
yahoo has been in ecommerce, shopping, travel, auction, jobs, books, dating, weather, mails, games, sports, auto, real estate, video, finance, search engine, news, fortune teller and others.. unfortunately yahoo is not good any of them.. yhoo is the bottom 10 of each category. more start ups acquisition, less revenues they project... it appears yhoo strategy is to eliminate competitions by buying them out, instead of enhancing yahoo's revenue stream... Yhoo is the jack of all trades and master of none...