Foden damaged ankle ligaments against Bath on Friday and England expect to be without the Northampton full-back for the Tests against Fiji, Australia, South Africa and New Zealand.
England will also be without Leicester flanker Tom Croft while scrum-half Ben Youngs and prop Alex Corbisiero both face a race against time to be fit.
As much as Foden will be missed, Robshaw is of the firm belief that England need to develop greater strength in depth if they are to topple world champions New Zealand.
Alex Goode and Mike Brown both played at full-back against South Africa in the summer and will be battling for the England 15 jersey this autumn.
"Foden and Croft are both in the leadership group with responsibility in the squad, so of course they will be massive losses to the side," said Robshaw, the England captain.
"But with that, it gives an opportunity to someone else to come in.
"The likes of Mike Brown and Alex Goode are both playing very well at the moment and I'm sure there will be other players who will push their credentials as well.
"Unfortunately, injuries are something that happens in our sport and we have to be able to react and have faith in the players coming in, not just to do a good job but do a great job and put pressure on another player to get back in the side.
"That's what you want in the squad. If you look at New Zealand, if they have a couple of injuries they might go two players deep and still have world-class players in that position who come in and do a great job.
"That's where we want to be as a national side - to have two or three quality international players in every position, so that if someone has to come in, you know they're going to do an excellent job."
Robshaw feels England will be wiser for their summer experience in South Africa, when they lost the first two Tests but bounced back to draw the third.
While far from the finished article, England must retain fourth place in the world rankings through the autumn in order to claim a vital top seeding for the 2015 World Cup.
"We've been to South Africa now and we've been to various countries in Europe as well, learning and taking little points out of those games," Robshaw said.
"There have been a lot of positives we can take from our performances, but also weaknesses which we have to eradicate.
"Hopefully we can be a bit more experienced, a bit wiser and do that now.
"Of course the end goal is the 2015 World Cup - we all know where we want to be then and what we want to achieve - but it's also about the here and now.
"We want to win every game but we have to break that down and work out how we're going to do that.
"In the autumn series, I don't think one game plan will apply to two opposition teams, let alone all four, so we do have to learn and adjust quickly."
Gilbert has released a new line of rugby cleats. The Gilbert Virtuo 8S is part of the exciting new product. Check it out.
The entire All Blacks apparel line has been updated for 2013/14. Check out the New Zealand All Blacks polo.
The Nike Tiempo is a solid rugby cleat and one of few styles still made from full-grain natural leather.
The Gilbert Blitz 8S rugby cleat is a great cleat at a great price of $69.99. Get a new pair of cleats today.
A cool looking all black rugby cleat with the high performance adidas is known for. Get in the Gear!
Wear the crest of the British and Irish Lions on your t-shirt. A great look for the summer.
The All Blacks Performance t-shirt is black with hints of blue from the training jersey. Very Cool.
The New Zealand All Blacks training jersey for 2013/14. Get in the Gear!
The USA Rugby Pro Alternate rugby jersey is perfect for any fan of the Eagles. Get yours to wear during the summer Test matches.
The NEW All Blacks 2013/14 jersey has arrived at World Rugby Shop. Dare to wear the colors of the All Blacks.