In the same way that in the IT market the onus is on the individual to ensure that s/he is trained (at their own expense) on whatever the most sought after process is - SAP, RSA or whatever - then so it will be the responsibility of the pilot to obtain new ratings.
Wrong! The IBM's, Compaq's and such likes of this World recruit graduates and people from other area's and then train them in specialisms. The vast majority who self fund are independant's who don't want to be tied to one employer.
The cost of achieving certification in SAP (or similar) is probably around 10% of the cost of obtaining an ATPL with Type rating. There is a good chance the IT starting salary will be more in to the bargain.