While I do believe in the Rapture prior to the tribulation and then the establishment of a 1,000 year reign, I have never been able to understand dispensationalism, especially concerning Israel. My understanding is that the two witnesses will testify to the gospel. It is the Jews of Israel who hear this gospel and believe in Jesus Christ as their LORD and SAVIOUR that are the portion of Israel that is saved.
Such a belief is not inconsistent with dispensationalism. I can not stress enough. There are not two different ways of salvation. All is by grace through faith in Jesus Christ alone. The one difference is that dispensationalists (and probably some non-dispensationalists) believe that the promises that God made concerning the land of Israel will be literally fulfilled as well. He brings remnant and non-remnant Israel into the land, gathering her from the nation. But it is Abraham’s seed both physically and spiritually that will ultimately inherit the promise.