Roy Hodgson is due to announce his squad for next month's friendly against Denmark on Thursday afternoon and Sunderland winger Johnson suspects if his recent form has not won him a recall, he can forget about the summer.
Asked if World Cup dreams had been on his mind, the 26-year-old wide midfielder said: "More so recently.
"I have thought about it a little bit more, but I think it all depends on this next squad if you are going to be there or thereabouts and in with a chance of going.
"I have just got to take each week as it comes. It's all a bit up in the air - there are that many players to choose from, people in form, people out of form, injuries.
"There's a long way to go and a lot can happen, but as an England player, you always have half an eye on a World Cup in Brazil."
England manager Hodgson paid a visit to the Stadium of Light earlier this month, ostensibly to cast an eye over Johnson following his return to top form.
However, events conspired against the former Middlesbrough and Manchester City winger as Wes Brown's fourth-minute dismissal forced manager Gus Poyet to employ him in a different role as his side slipped to a 2-0 Barclays Premier League defeat against Hull.