In an interview with the National Review's Robert Costa, House Majority Leader Eric Cantor was pretty clear:

No one is advocating a government shutdown.

Well, some people are! But not Cantor, apparently. Here's why:

“In order to avoid a government shutdown, we need 60 votes in the Senate and 218 votes in the House to pass a continuing resolution,” he explained. “To get 60 votes in the Senate, you need at least 14 Democrats to join Republicans and pass a CR that defunds Obamacare. Right now, I am not aware of a single Democrat in the Senate who would join us.  If and when defunding has 60 votes in the Senate, we will absolutely deliver more than 218 votes in the House.”

Basically, House Republican leadership is making "avoid a government shutdown" the core priority. Since "avoid a government shutdown" and "refuse to pass a CR that doesn't defund Obamacare" are mutually exclusive, that means "refuse to pass a CR that doesn't defund Obamacare" is off the table. Sorry, Ted Cruz.

It's possible, of course, that House Republicans could just ignore their leadership on this one and go for a shutdown anyway. But if you look at what key House conservatives are saying to their constituents during the August-recess townhalls, Cantor appears to be on fairly solid ground:

This could be the best of all possible worlds for Cruz, Mike Lee, Marco Rubio et al. They get the credit with conservatives for being willing to shut down the government to defund Obamacare but it never actually happens, and so they never have to take the blame for the consequences.