Many experts are convinced that, were Britain to quit the European Union following its a referendum on June 23, London would lose its spot as Europe's top financial industry centre.
The so-called Brexit could benefit other finance centres in the EU, above all Frankfurt with its large banking, stock market and financial services sector that has already lured many international institutions.
But for some people this is not a cause for celebration. For example, the Association of Foreign Banks in Germany warns against false expectations.
"Sometimes you hear ... that Frankfurt would be the winner of an exit by Britain from the EU," association head Stefan Winter, an executive at the Swiss bank UBS, said recently. "I think such expressions are premature in view of the many variables, unknowns and uncertainties about how things would go for the United Kingdom if they vote to leave."
But there is no getting around one fact: that banks if they want to provide services within the EU must have a legally established subsidiary based in an EU member state.
As the DZ Bank notes, a Brexit would mean that banks, "along with their personnel and infrastructure would have to leave Britain and transfer to the EU, most likely to such places as Paris, Dublin or Frankfurt."
Financial industry experts say it would by no means be certain that Frankfurt would win the race as the future alternative location for financial institutions.
Already, the city on the River Main is bursting at the seams: Affordable housing is scarce and streets are often clogged with traffic.
At the end of last year nearly 200 banks were based in Frankfurt, 80 per cent of these foreign institutes. The banking sector employs 62,500 people.
Frankfurt likes to advertise how close everything is, including the proximity to the headquarters of such watchdogs as the European Central Bank and the European insurance supervisory authority EIOPA.
As the Hesse state bank Helaba notes, with the new European Banking Authority under the ECB also making its headquarters in Frankfurt in 2014, the city had definitively established itself as the "capital of European supervision."
UBS executive Winter believes that the ECB itself with "a magnet-like effect, just as much as the large number of skilled employees, good infrastructure and last but not least the strongest national economy in the EU" are factors in Frankfurt's favour.
"But the other locations that have been named have in the past have shown considerable creativity when it came to attracting international companies."
Dublin, for one, has some good prospects. Many US financial concerns prefer Ireland's capital purely for language considerations. The major bank Citigroup has already announced plans to move its European headquarters for private banking to Dublin.
A competitor, Wells Fargo, already does considerable business there, while Credit Suisse has opened up a trading floor in the Irish capital.
Meanwhile Germany's largest bank, Deutsche Bank, is preparing for any eventuality.
"We are prepared for all the scenarios," bank co-chairman John Cryan told the recent general shareholders meeting. "Through its strong position in Frankfurt and London, Deutsche Bank is well set to make its way through possible short and long-term effects of a Brexit."
Right now, London is the heart of Deutsche Bank's investment banking business. Asked where the bank with its 9,000 employees in London might head to in the case of Britain's exit from the EU, Cryan told the Financial Times: "For us, if it's anywhere, it's Frankfurt."
But the British banker expressed caution about the overall situation. "Our view is people don't look often enough at the other side of the coin and ask what does a Brexit mean for Europe. There we have said it isn't very good at all."
A lot is at stake as well for the Frankfurt stock exchange company Deutsche Boerse. Just in March the company had agreed on a merger with the London Stock Exchange. If British voters approve the exit from the EU, the deal could prove costly for the Frankfurt side because there could then be a massive drop in the London exchange's value.
In the end, a lot would depend on how a possible "No" to the EU by British voters would be carried out in the financial sectors. At Helaba, economists believe a likely scenario would be a mutually face-saving "divorce settlement" between the EU and Britain.
Helaba chief economist Gertrud Traud said this could mean London keeping its dominant position as a financial centre. "In this case the hopes of many Frankfurt financial players of massively profiting from an exit by Britain would be premature."