Mega Man 10 is heading to WiiWare in under two weeks, but it looks like Mega Man 4 will be joining it soon in North America. The ESRB was nice enough to rate the title for the Virtual Console.
I would think Capcom would try to get this out before Mega Man 10’s release. But if it doesn’t hit this upcoming Monday, hopefully after playing some Mega Man 10 you will still have some Mega Man spirit in you and play through Mega Man 4 too. Or you could always just play it on the NES or in one of the collections it is featured in.