Based on average 2016 grid numbers, Lada's absence would leave 15 cars in competition - a scenario that would allow an event to be called off.
Article 15 of the championship's sporting code states a meeting can be cancelled if fewer than 16 cars are entered.
Ribeiro acknowledged that the move to introduce WTCC-2 had been necessary in part due to the high costs of TC1 cars, but denied it represented a threat to the series' prestige.
"We recognise the challenges being faced by drivers and teams to secure the finances required to race a TC1 World Touring Car," he said.
"While the WTCC will clearly remain the pinnacle of touring car racing, WTCC-2 will provide a good platform for aspiring World Touring Car champions of the future to showcase their talents on a global stage, compete for an FIA title, but at a reduced cost by limiting WTCC-2 to TCN2 specification cars, which are more affordable to prepare and maintain.
"WTCC-2 competitors will benefit from the high event organisation standards, global media exposure and promotional activities in common with the WTCC."
STILL ROOM FOR ETCC
Ribeiro added that WTCC-2 would not render the WTCC-supporting European Touring Car Cup redundant, even though TCN2 cars form the basis of the ETCC's top class.
Existing WTCC outfits Zengo Motorsport and Munnich Motorsport both competed in the ETCC last season with Honda Civics built to TCN2-specification, while Sebastien Loeb Racing also entered a pair of Peugeot 308s at the Nurburgring round.
"We're actually creating a more affordable ladder of progression," he continued.
"It's fair to say the jump from the ETCC to a TC1 World Touring Car is high so by creating WTCC-2, we're providing an achievable next step for career-focused drivers.
"We also have to remember that a number of the drivers and teams taking part in the ETCC don't have the resources, both in terms of time and finance, to undertake a greater programme of events than the six that are currently organised."
Volvo gave the World Touring Car Championship a major boost when it announced it would enter the series, but its ambitions don't stop there. JACK COZENS examines its programme, the S60 and what its arrival means for the WTCC
The 2012 World Touring Car champion says he never had the money to race cars. Yet 2015 is his 11th season in the WTCC. He talks STUART CODLING through his journey from motorsport fan to paid professional - for little more than £100,000