Eidos Montréal boss David Anfossi revealed that Shadow of the Tomb Raider has been playable for a year. He then said creating new IPs is hard and risky, which is why Eidos Montréal sticks to established IPs.
Source: N4G PC Eidos Montréal Boss: SotTR Has Been Fully Playable for a Year; Creating New IPs Is Very Difficult