The end of 'Photographic' discoveries in the attic?

I received a request the other day from a magazine who were interested in using a shot I took in 2005.
They were prepared to pay quite handsomely but they insisted it had to be 11" x 17" at 300dpi dimensions.
I hesitated before saying it was going to be big enough as the dimensions they were asking for were way beyond anything a DSLR's was capable of at that time.
Following that path does this mean that a digital photograph has diminished value as the quality is deemed insufficient?
It does seem a bit bonkers to me but if clients take this line then what is one to do?
Crafty upsizing and hope they do not notice?
Thankfully I did not have to do this as I shot it on a Phase One and they commented on the high quality, even though the back 'only ' had 22 megapixels.
But I fear that time is going to be pretty cruel to digital photography.
And not in commercial scenarios that I have just been talking about but the sheer survivability of images.
A friend of mine found some old photo's which dated back to the dawn of photography.
They were in an old album, and to access them all he had to do was open the album and there they were.
My first efforts at backing up my photo's in the early 1990's was onto floppy discs. I still have the discs but no machine to read them with, perhaps I will buy a drive when I get round to it and transfer the images or perhaps I will get hit by a number 53 bus before I do and they will be lost forever?
The situation is much the same with all the images I have recorded onto Zip drives (remember those?)
When CD recorders became affordable I switched to archiving all my work onto CD's.
I did this for a year or so with the burner hooked up to a computer which was expensive and state of the art but which of course became obsolete.
It was time for a new computer.
Gleaming, wonderful and new.
Horror of horrors it would not read a single CD I had burned.
Was it the CD's ? Had I recorded them in some silly incompatible format? I still don't know but fortunately I still had the negatives so I could rescan them.
When I started to shoot digitally I switched to backing up my work to external hard drives made by a reputable, and not so cheap, manufacturer.
All went well at first, then I had my first, and very predictable, hard drive failure. Fortunately I had all the important work double backed up onto DVD's.
Hard disc drive failure made me buy even more external HDD's, all seemed well and then the spectre of power supply failures started to raise its head. Simple I hear you say, buy another. The company no longer made them. I started to scour eBay for them and found them going for more than a price of a external HDD, it seemed I was not alone with my problem. I then investigated buying a housing to put the drive in and get the data off.
I bought the drive housing and opened up the power-supply-less drive only to discover that there was not one HDD in there but two. The manufacturer had, without announcing it, used two drives and the spread over two discs and I was well and truly stuffed.
Fast forward to 2012 and my backups are a myriad of servers (I use the excellent QNAP) cloud storage and good old DVD's.
I'm relatively confident that under my care that my work is safe.
But what happens when the work is no longer under my care.
When I die, will my children and grandchildren have the same interest as I do?
In 100 years time will my great grandchildren have any interest at all?
Will they go looking for DVD drives to read the discs which may well be unreadable by then? Or go searching online for power supplies for rotting pieces of junk that may no longer work ? Or try to get new bearings fitted to HDD's that have long since seized up?
Think back to my friend simply opening a neglected family album and discovering ancestral gold.
Without hard copies there is no way this will happen.