The Airport will not see and major transport improvements in the short to medium term. John Parkin has publicly stated this, just look at Bristol. It has flourished despite having pretty poor transport links compared to other airports. Just because Manchester arguably good transport links (I have yet to have an easy journey from Leeds to Manchester Airport) does not mean it can or will be any more successful than competing Airports.
The LCC have completely changed the market, people are quite happy to be in a queue, have to change trains and busses and take poor roads to get a cheap flight. This is the basis that Airports like Bristol have grown, and is the basis that LBA will grow. Yes, LBA has a LONG way to go, but it is heading in the right direction when many Airports and Aviation organisations are not. Transport links will not directly affect the growth of any Airport, it will simply improve the passenger convenience - but simply apply the Ryanair effect on Airports and no one cares if they are a buggery to get to, it's all about the £.
Manchester is bang next to a Motorway and has seen passenger numbers fall dramatically over the last 12 months, Leeds Bradford is a good treck from the nearest motorway and passenger numbers have soared over the last 12 months. One reason - the availability of cheap flights.