Hey Ya'll, (TL;DR is at the bottom of this comment)

I wanted to give an update on the merge discussions.

On January 12 we released lodash v4. From its release notes:

The year was also one of collaboration, as discussions began on merging Lodash & Underscore. Much of Lodash v4 is proofing out the ideas from those discussions. Lodash v4 would not be possible without the collaboration & contributions of the Underscore core team. In the spirit of merging our teams have blended with several members contributing to both libraries.

It bears repeating Lodash v4 would not be possible without the collaboration & contributions of the Underscore core team. Since the merge talks began 8 months ago, with our now blended core, and combined efforts, Lodash has continued to gain ground. The following stats were reviewed by core members of both libs and are meant to show how far we've come as a whole (blended core), where our cumulative priorities are, and where the community is. (Sorry for the stats dump)

From non-core contributions (taken 2015-Feb. 2016):

to number of releases (taken 2015-Feb. 2016):

to number of commits (taken 2015-Feb. 2016):

to repo traffic (taken Feb. 2016):

Lodash	Underscore
Lodash has 2.8x clones, 1.8x uniq clones, 5.6x views, & 3x the uniq visitors of Underscore

to surveys:

backbone survey

developer survey

to npm package dependents (taken Feb. 2016):

dependent growth compared to npm's registry growth (taken Jul. 2015):

and growth per month (taken Oct. 2015):

Lodash is the fastest growing npm package with ~1,000 new dependents each month

even total commits year over year (taken Feb. 2016):

Lodash (up 10%)	Underscore (down 65%)

With Jeremy taking a step back, Underscore core like @braddunbar @jridgewell @megawac already contributing to Lodash, combined with the community and momentum it makes sense to continue to focus our energy on Lodash.

TL;DR

So as to the merge I think it's already happened as Lodash v4. We share core contributors, @jridgewell has npm publish rights for Backbone/Lodash/Underscore, and the community has moved along with us. Thanks everyone for your input, comments, suggestions, and support!