Personally, I think the solution in finding people to group with is more in Turbine giving folks incentives to group - rather then merging servers. For years now, they've been making soloing/short-manning the preferred way to run the game for a lot of players- the majority, in my opinion - and they've done so with a host of design choices that need to be reversed if grouping is to become viable again. Yes, I think that merging the servers is both more trouble then it would be worth as well as creating more lasting problems then it would solve short-term. And I also think that grouping will continue to suffer until Turbine makes a conscious and concerted effort to make it more palatable. I'd go into the litany of reasons why grouping has suffered, but this isn't the thread for it and it's been mentioned chapter and verse elsewhere a great many times.
But, until those problems are corrected - any server merge will just be an exercise in futility because the core problems will remain.