The Lib Dems are in a strange position in that they put forward a portfolio of views that are probably quite popular with a large section of the electorate: centrist, pro-European, but they are currently struggling electorally. I expect a lot of the students, centre-left liberal middle classes that have jumped on Corbyn's bandwagon secretly wish he was fighting for a second referendum and challenging Brexit and maybe some find his economic policies too radical. But they are on board with him for his authenticity and challenge of the Tories, where they see the Lib Dems as being ineffective.
Next election they may find things even tougher, as the advance of Labour means they don't have as many seats where they can benefit from tactical voting by being in second place. Labour now has a huge bank of 'target seats' for the next election where they can overhaul Tories, whereas the Lib Dems list of realistic targets is much smaller: although a fall in the Tory vote would still bring another 10 or so seats within their grasp and getting their MP numbers back in to the 20s would be decent progress.
In a historical context, the Lib Dems (or Liberals) have been in similar positions before and come back, and just missed some opportunities that might have otherwise changed their fortunes. In 2017 they got 12 seats and 7.4% of the vote, which is similar to where they were for most of the post war years up till the 1980s. In the 1980s, when Labour split and the SDP formed as a centre left party out of Labour, they joined with the Liberals as the SDP-Liberal Alliance and suddenly had a large support base that threatened to alter the balance of politics. But the first-past-the-post system went against them, so when they were polling 23 - 25% in the 1980s they were returning 22/23 MPs and just splitting the opposition to Thatcher enabling her to have 100+ majorities from a similar vote share to that which Theresa May got in 2017!
After the Alliance broke up and the Lib Dems were at a low ebb in the late 1980s, Paddy Ashdown actually did a very good job as leader - back then people were asking the same kind of questions as now "what is the point of the Lib Dems" and he soon had them winning some stunning by election upsets where massive Tory majorities got overturned and it really put the skids under the Tories.
The Lib Dems' big opportunity was to get electoral reform so they had a proportional representation system which would potentially have put them in permanent government with one of the other two parties. After suffering repeated defeats to the Tories, Labour were cowed and desperate in the early 1990s and there was a movement within Labour to look to try and join closer to the Lib Dems as a way of getting the Tories out, and Ashdown would have pushed for PR as the price of a coalition. The 1992 election was predicted to be a hung parliament and that would have been the Lib Dems' moment, but the Tories got a surprise win, and then by the time 1997 came round, the country was in love with Blair and Labour rediscovered their self confidence and did not need to bother with PR or the Lib Dems.
Nevertheless this was a time of great advance in Parliament for the Lib Dems, they went from 20 MPs in 1992, to 46 in 1997, 52 in 2001, 62 in 2005 and 57 in 2010. During these years they were taking advantage of a general weakness of the Tories and were taking traditional Tory seats that the Tories won back on a large scale in 2015 when they knocked the Lib Dems back to 8. They also benefited from the youth vote and students, because Charles Kennedy was the one leader who stood up against the Iraq War, and because of their general progressive policies (they were to the left of Labour in those days) and opposition to tuition fees.
2010 was their watershed moment. Had the parliamentary arithmetic been a bit different with Labour as the largest party they could have gone into the centre-left coalition they always wanted and been able to moderate and exert influence on Gordon Brown. As it happened Clegg joined with the Tories, failed to get a proper push for PR (instead going for a referendum on AV which nobody was really interested in at that point), surrendered on tuition fees (against the will of the party), and having fought a campaign to the left of Labour, was then involved in a government pushing through right-wing regressive policies. The Lib Dems found themselves trotting out the mantras about austerity which just made them look not credible, if they believed in austerity so much why had they not campaigned for it? So that lost them a lot of credibility and their natural support base has now locked on Corbyn.
I think it will be a long route back however there is a glimmer...if the Tories make a shambles of Brexit and their vote collapses, and there starts to be more pressure on Corbyn over Brexit, the centre-left Remainers will start to drift back towards the Lib Dems, and they might start climbing slowly back at least to where they were in the late 1990s/early 2000s. Then perhaps one day their moment will come again where PR will be back as a possibility...