U.S. Navy officials have told the Taiwanese government that European firms have been found who will collaborate with the U.S. to build eight diesel-electric submarines for Taiwan. No European country was willing to build subs directly with Taiwan, for fear of offending China. But China is vulnerable right now, with the Olympics coming up next year in Beijing, and much international tumult because of bad manufacturing practices for Chinese exports.
Delivery timeframe is not given. Plus the crews must be trained. If China wants to invade Taiwan before the Olympics or even shortly thereafter, the subs will not arrive in time.
But if China does not have any particular timeframe for invading Taiwan, the submarines will be able to threaten China's sea lines of supply. Taiwanese boats will deter tankers from arriving and container ships from sailing with Chinese exports.
And the subs will be a force multiplier. As long as a couple subs make it to sea, American nuclear subs will be able to quickly intervene in the fight. When submarine-launched Harpoons are hitting Chinese ships, who can say if they are launched from Taiwanese boats or American submarines?