They should also add MTP variants of the old (plate carrier) NATO vests
Also, the closest helmet available that almost matches the MTP camo is probably the dark paint SF helmet

For reference, should BIS choose to make an MTP version of the NATO helmets. Revision do produce fabric helmet covers for their Batlskin helmets (upon which the Arma 3 NATO ECH is based):

Basic version (shown in UCP rather than multicam/MTP):
http://www.revisionmilitary.com/store/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/b/a/basic_full_cut.jpg
http://www.revisionmilitary.com/store/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/v/i/viper_helmetcover.jpg
http://www.revisionmilitary.com/store/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/v/i/viper_helmetcover_elastictrim_closeup.jpg

Enhanced version (this style is used by the Danish and British militaries on their new Revision "Cobra" helmets):
http://www.revisionmilitary.com/store/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/c/o/cobra_fullcut_enhanced_multicam_profile_720x613_72_rgb.jpg
http://www.revisionmilitary.com/store/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/c/o/cobra_fullcut_enhanced_multicam_helmetcover_top_720x612_72_rgb.jpg

Premium version (mesh fabric):
http://www.revisionmilitary.com/store/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/m/o/modernization_kit_-_essential_kit_final.jpg
http://www.revisionmilitary.com/store/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/v/i/viper_premium_helmet_cover_-_above_-_web2_1.jpg
http://www.revisionmilitary.com/wp-content/uploads/2014/05/Viper-Premium-Helmet-Cover-Back-Web.jpg