I don't share your optimism. In the UK we have the most vicious partisan right wing media in the western world and once the Covid-19 crisis is over they will turn their attention on destroying Keir Stamer. The Tories will dump Johnson if they think he is a liability and install someone they think is more likely to win and present themselves as a new government and the gullible electorate will just lap it all up.
The thing is Starmer is in that positive zone near Blair, as far as the Labour party is concerned that makes him electable.
Obviously it's very early in his tenor, and it's very easy to be popular when you have no policies, as they say, so the test in the next few years. A majority is probably a bit of stretch - stranger things have happened though - but a Labour led government is more than possible. The issue is always that a Labour leader who gets the support of the press is not normally a Labour leader who gets any support from their party. The SNP are the big problem - as long as they continue to win most seats in Scotland, Labour floaters in England panic about a coalition with the SNP, and Labour's chances are diminished nationally due too poor success in Scotland. Essentially leaving Labour with only one option - convincing enough Southern Tories to vote for them.** What's really need is a co-ordinated alliance of the left that takes in Labour, Green, SNP, Liberal Democrat and Plaid and stands a single candidate in each constituency, but unfortunately there's not enough common ground on key issues.
The issue's with the chasm between what he promised to get elected in the party and what he's delivering regards the Labour's left are already starting to show through. The Overseas Operations Bill will be a big test, if he whips for it, without significant amendments to it, then he risks left wing MPs resigning the whip or forcing him health into sacking them or becoming embroiled into an ongoing left v centre battle for 4 years with Corbyn - which will bring 'disunited Labour' back to the forefront and give the press a field day.
2029 is probably the earliest we could realistically see a majority Labour government, by which point the Tories will have likely ditched Johnson (if he takes them into 2024 election*)
*This assumes the election is in 2024, with the scrapping of the Fixed Term Parliaments Act due to be put through at some point in the next year or so, it will simultaneously abolish term limits - which it abolished itself, so without any legislation to re-instate term limits, Johnson can essentially call the election whenever he wants - which will obviously give him a huge advantage.
**For all that the 2019 Tory victory has been described as a landslide this is primarily to do with the 11.5% lead in the popular vote over Labour. (which bizarrely is 0.1% lower than the Lib Dems total vote, which might explain where a lot of the 40.0% who voted Labour in 2017 went and where Starmer needs to look out to).
An 80 seat majority wouldn't make me overly comfortable as a PM.
After all that's only 40 seats to lose, which isn't as uncommon as you'd think.
For example in 2005 won a 66 seat majority and then lost it in the 2010 election.
And in 2001 he had 167 seat majority, losing 101 seats in the 2005 election. (a similar loss would take away Boris's majority)
And in 1987 Thatcher won a landslide of 102 seats only for it to fall to 21 seats under Major.