Some of the communities are entirely new, while a few have already been planned or even approved but never got off the ground beyond that initial announcement stage. The previous approach by the government was to expand existing communities rather than establish new ones as it was more expensive to build new communities (I guess laying the infrastructure was complicated and expensive). Shaked's approach is that even though it is more expensive there is an inherent value in settling the empty land down south, in addition to retaking control over the land there.

Shaked says this plan will be coordinated between the Ministries of Housing, and of Finance along with the Prime Ministers Office, all of whom support the plan.

source: Israel Hayom

I would expect the, at least initially, cheap housing prices will be one big attraction for people to move to such towns, but it seems likely the government will also give additional tax benefits to people who move south.

To paraphrase Ray Kinsella, if you build it they will come. And more importantly if you make it cheap enough they will come.