In a vacuum, the Packers have several candidates arguably worthy of an extension. I can make a case for Blake Martinez, and to a much lesser extent, Kenny Clark and Dean Lowry, but on the whole I do not think the Packers should extend anybody at present.
The other candidates for an extension include Daniels, Bulaga, and Fackrell. Players who will be unrestricted free agents after this season include Allison, Tramon Williams, Crosby, and if they make the team in 2019, Spriggs, and Trevor Davis.
Let's take a quick look at the Packers available cap space for 2019.