Note: I recommend thoughtful and deep research to determine whether each "possible match" is truly a match before you add them together...
That's right it's possible! as seen through this Reference Guide (page 83 - or check table of contents for page) on Family Search there is now a method to upload Gedcom's on the new Family Tree. "Well won't it be making duplicates like we've all be trying to avoid"
Well no. See after you upload it Family Search runs comparison scripts and spits out back at you possible matches for you to review; people who are no different in your Gedcom than they are on family tree; and new people to add.
You'll review each person who has a possible match on Family Search by your "Gedcom Person" being on the left and "Family Search's Person" suggestion on the right then you can add information or mark it as "Not a Match" at your leisure.
What a beautiful thing huh?
The previous way of uploading had a cap of 2,000 persons in a Gedcom. I don't know if that stipulation holds true. An important note is that the larger the file the longer it will take to upload and compare. But, that should be fairly obvious.
Also -- what an amazing push for stories and photos recently huh? Cool stuff.