You asked about other jurisdictions. As you'll probably be aware (from cases like EU vs Microsoft and EU vs Google) European countries and culture tend to have much stronger protection laws for consumer and employee rights than the US does.
In the UK you could make a strong case, although such cases are not often undertaken. The current legislation is Part 2 of the Consumer Rights Act 2015, but the unfair contract terms clause goes back to at least the Unfair Terms in Consumer Contracts Regulations 1999. Basically the law protects a person in a situation where disparity of size and bargaining power have led to unfair terms in a contract (typically a large company offering "take it or leave it" standard terms) - and specifically if they create a significant disparity in the parties rights and obligations. In such a situation the company which drafted the terms alleged to be unfair must show they are reasonable. A list of common terms likely to be seen as unfair is provided. (Employment terms are covered by other laws but also aim to prevent abuses due to inequality of contracting power)
A company which sold a product like Windows 7/8/8.1 and then later said "we are changing our terms of support and forcing you to upgrade" (especially to a different product the user may not want, or a product that is maintained in a different way),would almost certainly be at substantial risk of falling foul of this.
It wouldn't matter if it was done by not providing the support/patches as originally implied (by custom or normal expectation) or as agreed in an explicit statement of support life cycle, or by saying "we have the right under the contract to do this", or by forcing what is essentially a change of product to get the updates. It also wouldnt matter how big they are, nor whether or not the user had already agreed "because I felt I had no choice". The law is there specifically to protect against abuses like this, so it is drafted to catch companies who try to find "wriggle room".
