The Belgian striker, who is currently on a season-long loan from Chelsea, has netted 10 Premier League goals this campaign after an impressive time with the Toffees.
However, Lukaku is due to return to Stamford Bridge this summer after also enjoying a successful loan spell at West Bromwich Albion last season.
If Everton are unable to secure the 20-year-old's services beyond his current deal, they will be limited for striking options, but Howard is confident that Martinez can do more good business whatever the outcome.
"The one thing with all good managers that Roberto Martinez shares is that he has a belief in his own ideas and his ability," he told talkSPORT
"If big Rom (Lukaku) has to go, or Nikica Jelavic has to be replaced, I think he believes in his ability to recruit players. So I don't worry about that."
On a personal level, USA international Howard also admitted that he would consider a move to the MLS at some point in future.
He said: "It's something I'd like to do. It would be a transition that would interest me - whether that's playing or working off the field.
"The timing would have to be right."