Google has a number of tools (Trends, Insights for Search and more obliquely Ngram Viewer) that provide a rough notion of trending interest in something. Running 'competitive intelligence' through these tools suggests that this type of research is in decline.
Trends and Insights for Search return very similar results, so I will focus on Insights for Search. Here is the historical data for worldwide searches of 'competitive intelligence':
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Of course there are caveats - the data should be taken as indicative rather than prescriptive. But the data is unlikely to be blatantly wrong - charts such as this one show that Google broadly knows what it is talking about.
Google Ngram Viewer, which looks at the use of words in books, shows that 'competitive intelligence' rose sharply from its early days around 1980 until the turn of the century and may have started to decline since:
Three explanations spring to mind. One is that the amount of research is not in decline, but it is being called something else. Google would therefore see fewer searches for 'competitive intelligence' but an increase in searches by another term. But this increase in another search term is not happening. See for example this chart:
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The second explanation is that the same amount of competitive intelligence is being done, but practitioners are searching less often for related topics. This seems unlikely, although one of the caveats about this data is that it shows searches as a % of all searches rather than in absolute terms. The number of searches may be growing but their share of all searches is falling, although that still means that competitive intelligence is losing importance.
The third explanation is that competitive intelligence is indeed in decline. Why would that be? The most obvious reason is that we have failed to prove its value. It may be that companies are competing less (surely not...). We can rule out a recessionary argument because this decline started in 2004 and we do not see declines in the Ngram for previous recessionary periods.