I think that GHash.IO would be a seriously interested potential buyer to expand their already massive mining operations.
I think a discuss fish would be very interested to buy btcguild through a middleman.
I would doubt that either pool would be interested in buying btcguild, at least in it's current state.
According to
https://blockchain.info/pools BTCguild only has ~5% of the network hashrate over the past 24 hours, this compares to 29% and 19% for discus fish and ghash respectivly, so both pools would be gaining relatively small amount of hashrate. This plus the fact that most mining is doing by large corporate farms which little of which is apparently done on BTCguild, making it to be not a great acquisition target.
I would say that BTCguild would likely be purchased by someone who is running a very small pool with under 1% of the network or by someone who is looking to start their own pool