the market will no longer exist later

... is what some markets do.

Perhaps: "Due to [capacity expansion] in the USA and Canada, North American demand for European imports is on the dedline and will disppear altogether in the medium term."

If we knew what market we were talking about, I'd prefer: "... North American demand for imported European [nuclear warheads] is on the dedline and will disppear altogether in the medium term.

As Tony has pointed out, there are two aspects to this question

1) Due to the capacity expansion, european exports to NA and Canada will decline

2) European exports to NA & Canada will become zero in the medium-term

Here is the translation:
Due to the capacity increase in the USA & Canada, the european exports to this market will decline, and finally in the medium term, it will lose its market share (to North america & Canada) altogether

German term (edited): Der Markt wird mittelfristig entfallen

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Note added at 1 hr (2006-08-02 15:25:01 GMT)
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If the vendors don't start doing more training, the mainframe market will dwindle, so it's in their interest to get involved.
http://www.vnunet.com/computing/features/2072215/mainframes-...
And the enterprise market will dwindle further because many of the enterprises themselves, will become extinct.
http://www.siliconvalleywatcher.com/mt/archives/2005/07/dead...
If the PS2 can't prove itself to be a great game system early on, it will inevitably fall back on the other features built in, especially the movie player, and eventually the PS2 software market will dwindle because no one is buying games for it.
http://www.planetgamecube.com/mailbagArt.cfm?artid=3301
Data compiled by IDC, a global market research and advisory firm, predicts that Window's share of the market will dwindle to 58 percent by 2007
http://www.vault.com/store/book_preview.jsp?product_id=38814


in the medium term
http://www.proz.com/kudoz/125303

mid-term: the halfway point in a semester or course, usually either the end of the first or third quarter. www.oswego.edu/academics/continuing/orientation/terms.html


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Note added at 8 hrs (2006-08-02 22:39:50 GMT)
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Harry and others are pushing very hard towards the zero concept. Only your context will tell you whether exports will vanish, disappear, be 'lost altogether', made redundant (sic) or simply 'dropped'.
In this case you could refine 'dwindle' to 'dwindle away' which, of course, signifies that they have ceased to exist.