How is that a valid argument? They're not even in the same industry, let alone the same "stage" (market?). But the examples are good - for the opposite argument. Very few of them had problems because of a new company entering the stage.
US Steel - down because of deindustrialization, but it's still big
Standard Oil - broken up almost immediately by antitrust law
AT&T - also split by antitrust lawsuit, but then bought back the split companies and it's big again
Union Pacific - lost the top position because BN (from BNSF) bought more railroads than them, but it's still the second. It's also kind of hard to grow if you have to build rail tracks... in US.
Pennsylvania Railroad - failed to compete with interstate highways built in 30s and jet airlines starting from 60s when their main revenue was declining industrial heavy freight.
International Mercantile Marine Co. - might be a valid example
American Tobacco Company - broken by antitrust laws
U.S. Rubber Co. - I don't think they were that big in 1910. There were a lot of competitors.
Central Leather Company - ran out of leather and the investors liquidated the company to buy oil and gas shares instead
Amalgamated Copper Mining Company - ran out of copper.