Twenty years ago today Scotland voted 3:1 for the establishment of a Scottish parliament. It was a very different political time: Diana’s death, Britpop and Bill Clinton in the White House.

It was clear the old Westminster system of governing Scotland was discredited. Voters recognised it was undemocratic, and produced bad politics and legislation. The case for change had become a consensus – “the settled will” in John Smith’s description – that the referendum merely validated.

Twenty years later devolution has been a success. There are no serious calls for the Scottish parliament to be abolished or for a return of direct rule from Westminster. Ruth Davidson and the Tories long ago made their peace. The late Tam Dalyell was the last expression of such a politics.

The Scottish public now view the Scottish parliament, rather than Westminster, as the most important political institution. Irrespective of formal independence, Scotland already has an informal independence of the mind in how it talks, thinks and acts.

Many good things have happened: land reform, the smoking ban, and a Scotland more at ease with itself on gender equality, sexual equality, sectarianism and multiculturalism. But in a politics supposedly about difference, many of these gains have been about making Scotland more cosmopolitan and like most other western countries.

All of this isn’t quite the brave new politics promised in 1997. Instead, much of Scottish politics looks like politics elsewhere, including Westminster. Political power sits not with the Scottish parliament, but with the Scottish government and civil service. There is an adversarial party politics and the remorseless centralisation of public bodies, such as the creation of Police Scotland, with little obvious gain. Scottish ministers gather more and more power into their hands with few checks and balances, or obvious benefits.

Beyond this there has been little devolution dividend: economically, socially, in public services, or in relation to what groups have power and influence. This could have embraced a distinct take on public service reform that widened the life chances of the disadvantaged, or tackled the systematic exclusion of working-class children from the opportunities they deserve.

The SNP until now has been able to ride two horses at the same time. It has positioned itself as the party of the insiders: of getting things done, delivery and competence. At the same time it has posed as the party of change: of social justice, fairness and the champion of social democracy.

This balancing act – of incumbency and insurgency – worked wonders for the party in the late, hectic stages of the 2014 indyref and the aftermath of the 2015 UK election. But after 10 years in office it has begun to look less and less sustainable and plausible.

Devolution had many midwives – Labour, the SNP, the Liberal Democrats, churches, trade unions, NGOs and wider civil society. Most important was a public consensus. But while the latter wanted change, it wasn’t quite clear what kind of change they wanted. For some, devolution was about a rejection of Thatcherism; for others a return to the certainty of the Britain of 1945-75, and a Scottish version of the best strands of this age: the NHS, welfare state and BBC.

Large parts of institutional opinion, and Labour in particular, didn’t want devolution to bring about change, but merely to refresh the shop window while leaving the business behind it untouched. Devolution was for Scottish Labour about shoring up its northern citadel, and contributing its bloc to Westminster Labour governments. It hasn’t quite worked like that.

Labour mini-devolution amounted to an apologetic politics, and was eventually viewed as ineffective by most voters. It was one reason the SNP won in 2007. It seemed to have a story about the Scottish parliament and a vision for Scotland, as well as confidence expressing it. Time has shown the limitations of the SNP, which raises questions about where the politics of change will come from, and who can most successfully adopt the party’s mantle.

Change is coming to Scotland. The decline of deference, demographics, Brexit, the squeeze on public spending and the wider age of disruption make this is a certainty. The SNP gave Scotland a distinct voice, but the next decade could be shaped by Nicola Sturgeon’s SNP, Davidson’s newly energised Tories, or a Corbynised Scottish Labour. Nothing in the future can be taken for granted.

Happy anniversary, Scottish parliament. We celebrate your existence, not as an end in itself, but as a catalyst for further change.

• Gerry Hassan is a Scottish writer, commentator and academic