'Horizon of expectations' is an accepted term in philosophy (see below) and I think you really need to preserve it. The notion was central to my Ph.D. thesis. It's the starting point of accumulated knowledge and experience from which you communicate.

If you don't want to use it, then I'd suggest using one of the alternatives I've posted. At the very least, it's referring to the level, not the breadth, of expectations.

Horizons of Expectation - Wikipedia
https://en.wikipedia.org/wiki/Horizons_of_Expectation
The phrase "Horizons of Expectation" is a term fundamental to German academic Hans Robert Jauss's Reception theory. ... According to Jauss, the reader approaches a text armed with the knowledge and experience gained from interactions with other texts.



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Note added at 1 hr (2017-11-04 02:50:45 GMT)
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I said 'communicate' -- It might have been better to say 'with which you approach a communication exchange'. The writer or speaker typically assumes your horizon of expectations and tries to match it. Similarly, the philosopher Paul Grice wrote about the "cooperative principle":

www.albany.edu/~zg929648/PDFs/Dynel.pdf
by M Dynel - ‎Cited by 5
In his seminal lecture published as an article, Grice (1989a [1975]) propounds the Cooperative Principle (CP) ... which gives rise to (conversational) implicature ...