The Chinese government already cracked obfs2. They can DPI it. They also enumerated all bridge IP addresses a couple of years ago. The Tor Project should be doing a better job of dividing the BridgeDB buckets and detecting mass enumeration attempts, but it's possible the NSA or other intelligence agencies could have enumerated them. OTOH, the churn might be high enough to supply a decent pool of IP addresses at any one time. So far there is no documented evidence that anyone can DPI obfs3. The answer to your question is that nobody knows for sure, but using an obscure VPN provider in combination with obfs3 bridges is your best option for membership concealment in the Tor network.