Welsh Rugby Union chairman Gareth Davies has warned of financial "pain" if games resume but are played without spectators.
Rugby has not been played since March because of the coronavirus crisis.
Wales are scheduled to host seven Test matches from October 2020 to March 2021 - four autumn internationals and a possible three Six Nations games.
"I have been asked this week to assess the impact of Covid-19 on Welsh rugby," Davies said.
"We are still very much in the eye of this storm and it will not be possible to fully answer this question until that storm subsides.
"The major issue we face is if matches resume behind closed doors, this will have repercussions as the majority of costs will be brought into play, yet local revenues such as ticket income and associated match-day revenues will not."
WRU chief executive Martyn Phillips has previously warned the governing body "would be looking at £50m of lost revenue" if Wales did not play any autumn or Six Nations games.
Wales have to play their postponed 2020 Six Nations game against Scotland and are due to host New Zealand, South Africa, Argentina and Fiji in their autumn international programme.
But if games are played without the WRU being able to maximise its revenue from tickets, hospitality and other associated business, Davies fears there will still be a significant financial strain.
"We do know that we generate much of our income from leisure and entertainment spending, whether that be stadium tours, conferences and events or our core business of Welsh professional rugby. This entire sector has suffered a cessation of business on a par with the worst-hit sectors of industry," Davies added.
"Since it opened, Principality Stadium has generated billions of pounds for the hotels, restaurants, bars and leisure industry in Wales as well as generating thousands of jobs - the knock-on effect will be widely felt and our pain will unfortunately be shared.
"It is still the case that we do not know when 'normal' business will resume. When Welsh rugby stadia will be full again and when new broadcast and sponsor income can be generated.
"The WRU does not retain profits but redistributes all funds back to clubs and the professional game, so all aspects of Welsh rugby have been challenged by the current crisis.
"When we do return, we know there will be numerous challenges around the resumption of contact sport and we don't know what the attitude of our players, coaches, referees and other volunteers in the community game will be."
Davies also said they will need the of help the Welsh Government to help them through the crisis but have not indicated yet whether that means financial assistance.
"We will look for support from government for our efforts to safeguard the future of rugby in Wales, be it rugby within schools or harder to reach communities," said Davies.
"The positive role of the club game across communities is an essential part of Welsh rugby and it must not be allowed to wither.
"We will continue to need the support of the government as critical advisers in our plans to return to rugby."