This is nonsensical for some very simple reasons. Firstly, people will always want information gathered, filtered, edited and packaged; and newspapers do this for us very effectively.
Aha, this could be done perfectly adequately online, you say. True. But - and this is the main point - people will also always want to consume this information in a flexible way: with regard to all the 'wheres' and 'hows' you can think of. The paper format allows that: on the escalator, up the scaffolding, next to the pool, in the cafe, second-hand at the doctor's waiting room, in the potting shed.
And not only can you read a paper just about anywhere but you can treat it as roughly as you want, short of setting it on fire (though this is useful too at barbecue time). You can even throw it against the wall and jump up and down on it if it makes you angry. Not your Kindle though, which you also wouldn't want to have to bring out at some of the locations above. Electronic media has not and will not achieve this level of usability.
Finally, the economic argument. When businesses in a shrinking sector are loss-making it's extremely rare for that sector to disappear. What usually happens is that the weakest businesses go bust allowing the smaller quantum of demand to be distributed in larger proportions, so restoring profitability.
This has happened in just about every business that's had its viability challenged due to technological change (stationery, film, carriages, bicycles, radio). Where a sector has disappeared it's been because it's had a very narrow, specific focus and the innovation has been able to replace its functionality like-for-like (quills, vellum, celluloid film, transistor valves).
Newspapers fall into the first category.
The precise number of surviving publications will be determined chiefly by how many can be supported profitably on a given quantum of demand. But supply factors could also be influential: from whether newspapers can be made more cheaply (newspapers printing excerpts from blogs for free with the blogger earning from the new traffic generated?) to proprietors happening to have a virtually limitless appetite for losses.
For what it's worth, my prediction would be that we end up in the UK with a couple of broadsheet papers and the same number of tabloids. Their revenue models would be the same as today's: free online and charging for hard copies. They'll be nicely profitable but not as influential as today's press. Separate Sunday editions will disappear (though the brands may live on).
In any event, people should stop anticipating the end of newspapers. It ain't gonna happen.