Well that's my question. Is it possible that stalemate is exactly what they are going for?
This is just my opinion but I think they are just waiting for the right moment. Playing for the long term or end game if you will. They know ultimately they will outlast the Taiwanese. It's just a matter of time and the Chinese are very patient. Whether it will take 5 months, 5 years, 50 years or 500 years they will bring Taiwan back into the fold. They will not rest until they get back all Chinese territory lost in the last dynasty (Korea, Vietnam excluded of course). For them it's a huge deal, a matter of national pride and recourse for the "Century of Humiliation". The Chinese have long memories. They are also pragmatic. They will wait it out.
Which is why they are riding it out slowly. The strategy is three fold:
1. Political: Isolate Taiwan
Move in on any Taiwan allies and induce them to switch diplomatic recognition from ROC to PRC (only 25 or so remain now). Most of them are in Africa, Latin America/Caribbean, and Pacific Islands. Prevent Taiwan from joining any international organizations such as UN and sub-groups, WTO, etc.
2. Economic:
Trade between PRC and ROC has increased dramatically in the last decade or so. A lot of Taiwanese money is tied up in Mainland investments. This makes it very tricky if tensions rise in the Straits and China decides to choke Taiwan economically. However, both sides are actively trying to increase contacts especially with the KMT back in power in TW and more Mainland friendly than the previous administration under the DPP, using the Three Links philosophy (direct mail/shipping, telecoms, and travel/flights).
China has successfully stunted Taiwanese growth as a regional trade power through posturing. For example, Taiwan is competitve and usually on a short list to be a hub for MNC looking to expand in the area. However, concerns over Straits stability and pissing off China has kept many major firms from making Taiwan their hub costing them lots of revenue. Previously, lack of direct shipping to China from TW was also costly.
During the 90's China would fire off some missles ("testing") in the Straits, usually during a Taiwanese election causing the TAIEX to fall and forcing flights and shipping to delay or reroute causing many comapnies to lose money. This type of disruption has cause TW to lose competiveness economically speaking.
3. Military:
China has always had a numerical (quantitative) superiority over Taiwan but was severly lacking in quality. China's inability to "invade Taiwan" stems from it's lack of naval capacity to launch amphibious assaults and landings. Even if it tried to bum rush TW with 2 million men in inflatable boats it would be pretty disastrous. Taiwan is a difficult island to take. The Allies decided against it in WWII and opted to bomb the shit out of it instead. Luckily for TW, back in the day, TW was able to procure decent weapons systems such as P-3s, anti-sub stuff, Aegis equiped DDGs (Knox or Perry, can't remember). Basically, just enough to foil or deter China from "going for it".
China's subs are not that great but great in number. I believe they are intended for 2 reasons: nukes and to block the Straits. Eventually they will get better maybe with the Jin class but will always be inferior to US subs but TW has not been able to upgrade their subs either.
TW's air force used to be pretty good with the upgrade to F-16s and Mirage 2000 but they don't have many. If China manages to get their JC 35 or whatever it's called, out in numbers, they may eventually have the capability to overwhelm them.
In short, TW has been slipping in having the edge in the past few years. Their own home grown defense has stagnated a bit and foreign supplier are drying up (US, etc are more and more reluctant to help them out even though they are bound by treaty).
Basically, at the end of the day, China will eventually surpass Taiwan and have all the cards. Whether or not it will be wise to use them is another story.
Anyways, this is just my opinion off the top of my head as I don't really have the time to get into it right now.