Verily. See on Matt. 5:18; John 1:51.
Is coming, and now is. While the phrase “is coming” clearly applies to the literal resurrection in the future (see v. 28), the words “now is” seem to point to the experience to which Jesus had just referred, when the Christian “is passed from death unto life” (v. 24). Thus they are a reminder that a spiritual resurrection is immediately available to anyone who, though spiritually dead, will yet “hear the voice of the Son of God.” See the similar use of these phrases in ch. 4:21, 23.
It is also true that the present verse appears to speak of only a partial resurrection, whereas v. 28 distinctly declares that in the future resurrection “all that are in the graves shall hear his voice.” So understood, v. 25 may be seen as referring to the special resurrection of many “saints which slept,” but arose at the resurrection of Christ as the first fruits of His victory (see Matt. 27:52, 53).