Good question. I think they are sending out mixed mesages a bit at the moment.
On the other hand, if you compare today's Witnesses with the rabid clegy baiting, politician hating, "fifth column" conspiracy theorist Jehovah's Witnesses Rutherford cultivated in the 1930s, then I would say the Witnesses have already become fairly mainstream actually, compared to what they were.
A big change I think was signalled in their flip flop over Romans 13. The governements are now seen as part of God's arrangement.
Read the old blue school brochure and notice how it was all geared up to how different Jehovah's Witnesses are and how they will not conform or compromise. Then compare that with the much more teacher friendly updated version where the emphasis is very much on how normal and eager to fit in Jehovah's Witnesses are despite their differences. I think that is one instance that signals a general change in attitude.
Another thing is how they changed from not cooperating with outside historians of the holocaust in researching Jehovah's Witnesses in the Nazi period in the 1980s, to actively engaging with the scholarly community in the 1990s.
Another thing is they began to seek recognition as a religious body under public law in Germany, a status that did not bother them before.
Over the short term small changes might be hard to discern in terms of impact and direction, but over the long term I think the trajectory toward the mainstream began a long time ago and has been steady.
Slim