Periodic tenancy

My tenants were due to renew their contract at end-April (so in one month) and all had been agreed before the outbreak. Of course now they are worried about ability to pay and don’t want to sign a new contract. They’ve asked for a periodic tenancy to get over this 2-3m period. If I say yes, what are the implications for me? All I already know is they will have a 1m motif period, whereas the contract has 2m. What else should I be worried about?