But Ritchie, who is on the Lions board, said "proper and adequate" preparation for the Lions squads would be achieved, following recent talks with the English premiership clubs.
He also wants Lions coach Warren Gatland to talk to those clubs about what is needed to ensure Lions teams can be successful. This could precede the new 12-year agreement with New Zealand, South Africa and Australia.
However, Ritchie - who is in New Zealand - confirmed to the Telegraph that Lions tours would be reduced from 10 to eight games.
Current tour manager John Spencer, a member of the legendary 1971 Lions team in New Zealand, says this would jeopardise the Lions future because teams would be ill-prepared for the test series.
Ritchie said: "It was quite categorically agreed in San Francisco that the next 12 years would be protected (for Lions tours). One of the reasons why the agreement on the calendar went to 2032 was so that there was a Lions tour to each (South Africa, Australia and New Zealand).
"The eight-match schedule was also agreed by all the SANZAAR companies, agreed by the northern hemisphere, the Lions board and PRL (Premiership Rugby)."
Any reduction poses another problem, according to Lions chief executive John Fehan, who says the loss of revenue to the host countries could impact the deal allowing northern countries to keep the profits from in-bound tours.