If you accept only altcoins as collateral you will be pretty safe, no doubt about it but you will probably not be able to give any loan because there are other people that give loans and accept other collaterals or some of them even give loans without collateral
Yes accepting alt coins as collateral is the safest but I guess 2-3 out of 10 asking for a loan uses alt coins as collateral. I read somewhere one is asking for a loan and someone asked for alt coins as collateral, reply is if he is in possession of an alt coins he might as well trade it than ask for a loan.
